JP2019219246A - Magnetic field simulation program, information processing device, and magnetic field simulation method - Google Patents

Abstract

To detect an inaccurate simulation result when shortening the calculation time of a micromagnetic simulation.SOLUTION: An information processing device 1 approximates the magnetostatic field vector of each element for each time of day using magnetization vector data when simulating the state of magnetization vector of each element that is obtained by dividing a magnetic substance into meshes. The information processing device 1 calculates, for each element, magnetization vector data at the next time of day using magnetostatic field vector data at a specific time of day. The information processing device 1 calculates, for each element, a change amount of magnetization vector data between the specific time of day and the next time of day. The information processing device 1 discontinues a simulation on the basis of the change amount of respective magnetization vector data having been calculated for each element, and outputs to the effect that the simulation has been discontinued.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic field simulation program, an information processing device, and a magnetic field simulation method.

  As a technique for analyzing the magnetization behavior of a magnetic material, a micromagnetic simulation that models a magnetic material as a set of small magnets and numerically simulates a magnetic domain state is known. The micromagnetic simulation is used to analyze a magnetic domain state of a magnetic material such as a magnetic head of an HDD (Hard Disk Drive) or a magnetic random access memory (MRAM), and a magnetic material such as a permanent magnet or an electromagnetic steel plate.

  FIG. 11 is a diagram for explaining modeling of a magnetic material by micro-magnetization. Here, the micromagnetization is an individual small magnet. As shown in FIG. 11, in the micromagnetic simulation, a magnetic material is divided into minute elements (mesh), micromagnetization 91 is arranged for each element, and the behavior of each micromagnetization 91 is calculated as a magnetization vector 92.

In the micromagnetic simulation, an equation governing the motion of each micromagnetization (governing equation) is Equation (1), and is called an LLG (Landau-Lifshitz-Gilbert) equation.

Here, m, γ, α with “→” above and the effective magnetic field vector H _{eff with} “→” above are a magnetization vector, a gyromagnetic constant, a damping constant, and an effective magnetic field vector, respectively. . “→” indicates a vector. Hereinafter, “→” indicating a vector is used only in the expression, and is omitted in other places. “X” indicates a cross product.

Effective magnetic field vector H _eff, as in the equation (2), different directions energy E _ani, exchange coupling energy E _exc, is the synthesis of Zeeman energy E _app and the magnetostatic energy E _d. Here, Ms is the saturation magnetization.

Different direction energy E _ani, exchange coupling energy E _exc, Zeeman energy E _app and the magnetostatic energy E _d are each formula (3), Equation (4), is calculated by Equation (5) and (6).

Here, k, K _u , A, M _{s with} “→” above and H _app with “→” above are the magnetic anisotropy vector, magnetic anisotropy constant, exchange coupling, respectively. Constant, saturation magnetization and external magnetic field vector.

H _d where "→" is attached to the above, a static magnetic field vector is calculated by the equation (7) and (8). Here, φ is a magnetostatic potential.

  A reference example of a flowchart in which the information processing device performs a magnetic field simulation as a micromagnetics simulation will be described with reference to FIG. FIG. 12 is a diagram showing a reference example of the flowchart of the magnetic field simulation. As shown in FIG. 12, the information processing apparatus first generates calculation data necessary for a magnetic field simulation (step S91). For example, the information processing device generates a mesh from a target magnetic body. The information processing apparatus generates a magnetostatic potential region P for each mesh. The information processing device generates, for each mesh, a region M where a magnetization vector is arranged.

  Then, the information processing device sets various parameters necessary for the magnetic field simulation (step S92). For example, the information processing device sets an initial value of the magnetostatic potential for each mesh. The information processing device sets an initial value of the magnetization vector for each mesh. The information processing device sets the maximum time step kmax.

  Then, the information processing apparatus repeatedly executes the processing sandwiched between step S93 and step S97 on the magnetization vectors m (i) of all the meshes until a predetermined time kmax for each time step. That is, the information processing device updates the magnetostatic potential φ using Expression (8) for each mesh i (Step S94).

The information processing device updates the magnetic field vector for each mesh i (step S95). For example, the information processing apparatus, using Equation (7) and (8), and updates the static magnetic field vector H _d gradient calculation of magnetostatic potential phi. Further, the information processing device updates the external magnetic field vector H _app , the magnetic anisotropy vector k, and the exchange coupling magnetic field vector (∇m) ² .

  Then, the information processing device updates the magnetization vector m (i) for each mesh i (step S96). For example, the information processing apparatus updates the magnetization vector m (i) by Expression (1) using Expressions (2) to (6) (Step S96).

  When the repetition for a predetermined time is completed, the information processing device outputs a simulation result of the magnetization vector.

JP-A-10-124479 JP-A-10-325858 JP 2008-275403 A

Incidentally, in the micromagnetics simulation requires a large computational time, the majority of the calculations of the static magnetic field vector H _d (Equation (7)) the calculation of the magnetostatic potential φ used in (Equation (8)) occupies its ing. Therefore, the calculation of the static magnetic field vector H _d, do not perform the calculations of the magnetostatic potential phi, it can also be carried out by Equation (9). Incidentally, N, mu ₀ denotes demagnetization factor, the magnetic permeability of vacuum.

When the static magnetic field vector _Hd is implemented by Expression (9), there is a problem that the calculation of the simulation may be inaccurate. That is, by the static magnetic field vector H _d is performed by equation (9), it is possible to omit the calculation time of the magnetostatic potential phi, to shorten the calculation time of the simulation. However, calculation of the static magnetic field vector H _d because of approximation, in some cases, a simulation calculation is broken, it may become inaccurate simulation results.

  In one aspect, an object of the present invention is to detect an incorrect simulation result when shortening the calculation time of a micromagnetic simulation.

  In one aspect, a magnetic field simulation program disclosed in the present application, when simulating a state of a magnetization vector of each element obtained by dividing a magnetic material into meshes, converts static magnetic field vector data of each element at each time into a magnetization vector. Approximate using data, for each element, calculate the magnetization vector data at the next time using the static magnetic field vector data at a specific time, and calculate the magnetization vector at a specific time and the next time for each element. The computer is caused to execute a process of calculating a change amount of data, stopping the simulation based on the change amount of the magnetization vector data calculated for each element, and outputting a message indicating that the simulation is stopped.

  According to one embodiment, an incorrect simulation result can be detected when the calculation time of the micromagnetic simulation is reduced.

1. FIG. 1 is a functional block diagram illustrating the configuration of the information processing apparatus according to the first embodiment. FIG. 2 is a diagram illustrating an example of data. FIG. 3A is a diagram (1) illustrating an example of a characteristic of a magnetization change amount. FIG. 3B is a diagram (2) illustrating an example of a feature of the magnetization change amount. FIG. 4 is a diagram illustrating an example of a flowchart of the magnetic field simulation according to the first embodiment. FIG. 5 is a diagram illustrating an example of a flowchart of a magnetization change amount calculation process according to the first embodiment. FIG. 6 is a diagram illustrating an example of a magnetic body model to which the first embodiment is applied. FIG. 7 is a diagram illustrating an example of the result data according to the first embodiment. FIG. 8 is a diagram illustrating an example of a flowchart of a magnetic field simulation according to the second embodiment. FIG. 9 is a diagram illustrating an example of a flowchart of a magnetization change amount calculation process according to the second embodiment. FIG. 10 is a diagram illustrating an example of a computer that executes a magnetic field simulation program. FIG. 11 is a diagram for explaining modeling of a magnetic material by micro-magnetization. FIG. 12 is a diagram showing a reference example of the flowchart of the magnetic field simulation.

  Hereinafter, embodiments of a magnetic field simulation program, an information processing device, and a magnetic field simulation method disclosed in the present application will be described in detail with reference to the drawings. Note that the information processing device is a device that performs a micromagnetics simulation, and calculates and displays a magnetization vector for a predetermined time at fixed time steps. In addition, the present invention is not limited to the embodiments, and is widely applicable to magnetic field simulation.

[Configuration of Information Processing Device]
FIG. 1 is a functional block diagram illustrating the configuration of the information processing apparatus according to the embodiment. As shown in FIG. 1, the information processing device 1 includes an input unit 2, a display unit 3, a storage unit 4, and a control unit 5.

  The input unit 2 is an input device for a user who performs analysis to input various information and instructions to the information processing device 1. For example, the input unit 2 corresponds to a keyboard, a mouse, and a touch panel. The display unit 3 is a display device that displays various information. For example, the display unit 3 corresponds to a display and a touch panel.

  The storage unit 4 is, for example, a semiconductor memory device such as a RAM or a flash memory, or a storage device such as a hard disk or an optical disk. The storage unit 4 stores mesh data 41, calculation condition data 42, magnetization vector data 43, and magnetic field vector data 44.

  The mesh data 41 is data composed of a plurality of elements obtained by dividing a magnetic material region to be simulated into a finite number by a finite element method or a finite difference method. An element is an area of a minimum unit obtained by dividing an area to be simulated, and is composed of a plurality of nodes.

  The calculation condition data 42 is data on calculation conditions of the magnetic field simulation. The calculation condition data 42 includes, for example, the number of individual elements of the mesh handled by the finite element method or the finite difference method, and the value of the time step.

  The magnetization vector data 43 is data of a magnetization vector indicating a result of a magnetic field simulation, that is, a micromagnetic simulation. The magnetization vector data 43 includes a calculated value of the magnetization vector of each element for each time step for a predetermined time.

  The magnetic field vector data 44 is data of a static magnetic field vector used when calculating the result of the magnetic field simulation, that is, the micromagnetic simulation. The magnetic field vector data 44 includes a calculated value of a magnetic field vector such as a static magnetic field vector of each element in each time step for a predetermined time.

  The control unit 5 corresponds to an electronic circuit such as a CPU (Central Processing Unit). The control unit 5 has an internal memory for storing programs and control data that define various processing procedures, and executes various processing by these. For example, the control unit 5 executes a magnetic field simulation process. In the magnetic field simulation processing, the calculation is started by reading the mesh data 41 and the calculation condition data 42 from the storage unit 4. Then, the magnetic field simulation process checks the calculation result when calculating the magnetization vector of each mesh every time, stops the process before the calculation fails, and notifies the user of the stop.

  The control unit 5 includes a preprocessing unit 51, a magnetic field calculation unit 52, a magnetization calculation unit 53, a magnetization change amount determination unit 54, and an abnormal output unit 55. The magnetic field calculator 52 is an example of a magnetic field vector calculator. The magnetization calculation unit 53 is an example of a magnetization calculation unit. The magnetization change amount determination unit 54 is an example of a change amount calculation unit. The abnormality output unit 55 is an example of an output unit.

  The preprocessing unit 51 performs preprocessing before the magnetic field simulation processing. For example, the pre-processing unit 51 generates the mesh data 41. Further, the preprocessing unit 51 generates a magnetization vector to be arranged in each element of the mesh data 41 and sets an initial value. Further, the pre-processing unit 51 sets various parameters necessary for the magnetic field simulation processing.

  When simulating the state of the magnetization vector of each element, the magnetic field calculation unit 52 calculates the magnetic field vector of each element at each time.

For example, the magnetic field calculator 52 uses the equation (9), calculates the static magnetic field vector _{H d.} That is, the magnetic field calculation unit 52 approximates the static magnetic field vector without calculating the magnetostatic potential. Incidentally, N, mu ₀ in equation (9), the demagnetizing factor is the permeability of vacuum. Ms in the equation (9) is a saturation magnetization. Thus, the magnetic field calculator 52 is omitted computation time of magnetostatic potential φ of the formula (8), to approximate the static magnetic field vector H _d, can be consequently reduce the computation time of the magnetic field simulation It becomes.

In addition, the magnetic field calculation unit 52 calculates the external magnetic field vector H _app . The magnetic field calculation unit 52 calculates an external magnetic field vector H _app . The magnetic field calculator 52 calculates a magnetic anisotropy vector k. The magnetic field calculation unit 52 calculates an exchange coupling magnetic field vector (∇m) ² .

  Further, the magnetic field calculation unit 52 stores the calculation results of various magnetic field vectors in the storage unit 4 as magnetic field vector data 44.

The magnetization calculation unit 53 calculates a magnetization vector at the next time using a magnetic field vector at a specific time for each element. For example, the magnetization calculation unit 53 calculates various energies by substituting the various vectors calculated by the magnetic field calculation unit 52 into Expressions (3) to (6). Then, the magnetization calculation unit 53 calculates the effective magnetic field vector H _{eff according} to Expression (2). Then, the magnetization calculation unit 53 calculates the magnetization vector at the next time by substituting the effective magnetic field vector H _eff into Expression (1).

  Further, the magnetization calculation unit 53 stores the calculation result in the storage unit 4 as the magnetization vector data 43.

  The magnetization change amount determination unit 54 determines the amount of change in the magnetization vector. For example, the magnetization change amount determination unit 54 calculates the change amount of the magnetization vector between a specific time and the next time for each element. Hereafter, the change amount of the magnetization vector is synonymous with “magnetization change amount” or “magnetization change amount”. The magnetization change amount determination unit 54 acquires the maximum value of the change amount of each magnetization for each element. The magnetization change amount determination unit 54 determines whether the acquired maximum value of the change amount is larger than the threshold value of the change amount.

  The threshold value of the change amount is defined by the operator when the calculation of the magnetization simulation is executed. If the time interval between the specific time and the next time is large, the number of time integrations is reduced, so that the calculation time is shortened, but the amount of magnetization change per hour step is increased. In the magnetization simulation, it is necessary to handle the precession of magnetization (the first term on the right side of Expression (1)), and when the amount of change in magnetization is large, the accuracy of analysis is significantly reduced. Therefore, it is necessary for an operator to define the threshold value and the time interval of the magnetization change amount in consideration of the balance between the calculation time and the calculation accuracy.

Here, a method of calculating the amount of change in the magnetization vector between a specific time and the next time will be described. The magnetization vector of the element i at a specific time k is set as m _i ^k . The magnetization vector of the element i at the next time k + 1 is set to m _i ^{k + 1} . In such a case, the magnetization change amount determination unit 54 calculates the change amount dm _i ^k of the magnetization vector by Expression (10).

Then, the magnetization change amount determination unit 54 acquires the maximum value dm of the calculated change amount dm _i ^k of each magnetization for each element. The magnetization change amount determination unit 54 determines whether or not the obtained change amount dm is larger than the change amount threshold value dm_max.

  The abnormality output unit 55 outputs an abnormality. For example, when the maximum value of the amount of change is larger than the threshold value of the amount of change by the magnetization change amount determining unit 54, the abnormal output unit 55 stops the magnetic field simulation and notifies the user of the stop. Thereby, the abnormal output unit 55 can detect an inaccurate magnetic field simulation result when shortening the calculation time of the magnetic field simulation. As a result, the user can avoid receiving an incorrect magnetic field simulation result.

[Example of data]
Here, an example of the data will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of data.

  2 is an example of the mesh data 41. As shown in the left diagram of FIG. 2, in the mesh data 41, the position of each element obtained by dividing the magnetic material into meshes is set. The mesh data 41 is generated by the pre-processing unit 51.

  FIG. 2 shows an example of the magnetization vector data 43. As shown in the diagram in FIG. 2, the magnetization vector of each element for each time step is set in the magnetization vector data 43. The magnetization vector data 43 is updated by the magnetization calculation unit 53.

  2 is an example of the magnetic field vector data 44. As shown in the diagram in FIG. 2, the magnetic field vector data 44 is set with the magnetic field vector of each element for each time step. The magnetic field vector data 44 is updated by the magnetic field calculator 52.

[Example of characteristics of magnetization change amount]
Next, an example of the characteristics of the magnetization change amount will be described with reference to FIGS. 3A and 3B. 3A and 3B are diagrams illustrating an example of the characteristics of the amount of change in magnetization. The magnitude of the magnetization vector shown in FIGS. 3A and 3B is set to 1 because it is standardized and handled in the magnetization simulation.

  As shown in FIG. 3A, for element i, the magnetization vector is updated from time k to time k + 1. In such a case, the magnetization vector is inverted, and the magnetization change amount indicates “2”. That is, this is the case where the amount of change in magnetization becomes extremely large. In such a case, since the vibration of the magnetization is propagated from the element i, the magnetic field simulation processing results in an inaccurate result. Therefore, it is necessary to stop the calculation of the magnetization simulation. That is, if the maximum value of the change amount of each magnetic element is larger than the threshold value by the magnetization change amount determining unit 54, the abnormal output unit 55 stops the calculation of the magnetization vector data and notifies the stop.

  As shown in FIG. 3B, for element i, the magnetization vector is updated from time k to time k + 1. In such a case, the magnetization vector rotates 90 degrees, and the magnetization change amount indicates “1”. That is, the case where the amount of change in magnetization is not extremely large. In such a case, since the oscillation of the magnetization does not propagate from the element i, the magnetic field simulation processing gives accurate results.

[Flow chart of magnetic field simulation]
FIG. 4 is a diagram illustrating an example of a flowchart of the magnetic field simulation according to the first embodiment.

  As shown in FIG. 4, the preprocessing unit 51 generates calculation data (Step S11). For example, the preprocessing unit 51 generates the mesh data 41 used in the magnetic field simulation. The preprocessing unit 51 generates the magnetization vector data 43 used in the magnetic field simulation.

  Then, the preprocessing unit 51 sets various parameters (Step S12). For example, the preprocessing unit 51 sets an initial value of the magnetization vector data 43. The preprocessing unit 51 sets kmax, which is the maximum number of steps. The preprocessing unit 51 sets dm_max, which is a threshold value of the amount of change.

  Then, the information processing apparatus 1 repeatedly executes the processing sandwiched between steps S13 and S17 up to the maximum step number kmax for each time step k. That is, the magnetic field calculation unit 52 updates the magnetic field vector including the static magnetic field vector for each element (Step S14). Then, the magnetization calculation unit 53 updates the magnetization vector for each element (step S15). Then, the magnetization change amount determination unit 54 calculates, for each element, a change amount (magnetization change amount) of the magnetization vector between the time step k and the previous time step k-1. Then, the magnetization change amount determination unit 54 calculates the magnetization change amount dm for this time step k from the magnetization change amount for each element. The flowchart of the magnetization change amount calculation processing will be described later.

  Then, the magnetization change amount determination unit 54 determines whether the magnetization change amount dm is larger than the change amount threshold value dm_max (step S16). When it is determined that the magnetization change amount dm is equal to or less than the change amount threshold value dm_max (Step S16; No), the information processing apparatus 1 proceeds to Step S13 to add 1 to the time step k. When the time step k reaches the maximum number of steps kmax, the information processing apparatus 1 ends the magnetic field simulation.

  On the other hand, when it is determined that the magnetization change amount dm is larger than the change amount threshold dm_max (step S16; Yes), the abnormal output unit 55 stops the magnetic field simulation and notifies the stop (step S18).

[Flowchart of magnetization change amount calculation processing]
FIG. 5 is a diagram illustrating an example of a flowchart of a magnetization change amount calculation process according to the first embodiment. In the flowchart of FIG. 5, the loop for the element i at the time k is performed to calculate the magnetization change amount dm at the time k.

  As shown in FIG. 5, the magnetization change amount calculation processing initializes the magnetization change amount dm (step S21). The magnetization change amount calculation processing is performed on all elements while changing i, with the processing sandwiched between step S22 and step S30 as processing for element i.

For each element i, the magnetic field calculator 52 updates the static magnetic field vector _{H d} (step S23). For example, the magnetic field calculator 52, the equation (9), and updates the static magnetic field vector _{H d.} Then, magnetization calculation section 53, by the equation (6), to calculate the magnetostatic energy _{E d} with a static magnetic field vector _{H d.} Then, magnetization calculation section 53 uses the magnetostatic energy E _d, and calculates the fourth term of the equation (2).

The magnetic field calculation unit 52 updates the external magnetic field vector H _app for each element i (step S24). For example, the magnetic field calculation unit 52 updates the external magnetic field vector H _app . Then, the magnetization calculation unit 53 calculates the external magnetic field energy E _app using the external magnetic field vector H _app by Expression (5). Then, the magnetization calculation unit 53 calculates the third term of Expression (2) using the external magnetic field energy H _app .

The magnetic field calculation unit 52 updates the anisotropic magnetic field vector k for each element i (Step S25). For example, the magnetic field calculation unit 52 updates the magnetic anisotropy vector k. Then, the magnetization calculation unit 53 calculates the anisotropic energy E _ani using the magnetic anisotropy vector k by Expression (3). Then, the magnetization calculation unit 53 calculates the first term of the equation (2) using the anisotropic energy E _ani .

For each element i, the magnetic field calculation unit 52 updates the exchange coupling magnetic field vector (∇m) ² (step S26). Note that m is a magnetization vector. For example, the magnetic field calculation unit 52 updates the exchange coupling magnetic field vector (Δm) ² . Then, magnetization calculation section 53, by the equation (4), calculates the exchange coupling energy _{E exc} using an exchange coupling magnetic field vector ^{(∇m) 2.} Then, the magnetization calculation unit 53 calculates the second term of Expression (2) using the exchange coupling energy _Eexc .

For each element i, the magnetization calculation section 53 updates the magnetization vector _{m i} (step S27). For example, the magnetization calculation unit 53 calculates the effective magnetic field vector H _eff using Expression (2). Then, magnetization calculation section 53 uses the effective magnetic field vector _{H eff} calculated to calculate the equation (1), and updates the magnetization vector _{m i.}

For each element i, the magnetization change amount determination unit 54 calculates the magnetization variation dm _i (step S28). For example, the magnetization variation determining section 54 calculates the magnetization variation of the vector m _i (magnetization change amount) dm _i the time step k-1 time steps k and the previous.

Then, the magnetization change amount determination unit 54 updates the magnetization change amount dm (Step S29). For example, the magnetization change amount determination unit 54, among the magnetic variation dm _i for each element i, and updates the maximum magnetization variation dm _i as the magnetization variation dm. That is, the magnetization change amount determination unit 54 updates the magnetization change amount dm at the time k.

Then, the magnetization change amount determination unit 54 calculates the magnetization variation dm _i for all elements i, the process ends and calculating a magnetization variation dm.

[Example of magnetic material model]
FIG. 6 is a diagram illustrating an example of a magnetic body model to which the first embodiment is applied. 6 shows a single-layer magnetic thin film model as a magnetic material model. The single-layer magnetic thin film model is a model in which the magnetic thin film is a single layer. The right side of FIG. 6 shows a multilayer magnetic thin film model as a magnetic body model. The multilayer magnetic thin film model is a model when the magnetic thin film is a multilayer.

[Example of result data]
A result of executing a magnetic field simulation according to the first embodiment using such a magnetic material model will be described. FIG. 7 is a diagram illustrating an example of the result data according to the first embodiment.

  In the magnetic field simulation according to the first embodiment, the threshold value dm_max of the magnetization change amount was set to 0.1. In such a case, the information processing apparatus 1 normally executes the calculation of the magnetic field simulation without failing to determine the magnetization change amount using the threshold dm_max.

FIG. 7 shows the total calculation time when the magnetic field simulation according to the first embodiment is executed and when the conventional magnetic field simulation is executed. The conventional magnetic field simulation refers to the magnetic field simulation shown in FIG. That is, in the conventional technique, the calculation of the static magnetic field vector H _d, is the magnetic field simulation technique in the case of carrying out the calculation of the magnetostatic potential phi. In FIG. 7, the magnetic field simulation according to the first embodiment is referred to as a new method, and the conventional magnetic field simulation is referred to as a conventional method.

  According to FIG. 12, when the magnetic material model is a single-layer magnetic thin film, the total calculation time of the new method is 152 seconds, and the total calculation time of the conventional method is 8042 seconds. Therefore, the new method was able to reduce the total calculation time to about 1/50 compared to the conventional method. When the magnetic material model is a multilayer magnetic thin film, the total calculation time of the new method is 165 seconds, and the total calculation time of the conventional method is 4633 seconds. Therefore, the new method was able to reduce the total calculation time to about 1/30 compared to the conventional method.

[Effect of Embodiment 1]
In this way, in the first embodiment, the information processing apparatus 1 simulates the static magnetic field vector data of each element at each time when simulating the state of the magnetization vector of each element obtained by dividing the magnetic body into meshes. Approximation is performed using magnetization vector data. The information processing device 1 calculates magnetization vector data at the next time using static magnetic field vector data at a specific time for each element. The information processing apparatus 1 calculates, for each element, the amount of change in the magnetization vector data between a specific time and the next time. The information processing device 1 stops the simulation based on the amount of change in the respective magnetization vector data calculated for each element, and outputs a message indicating that the simulation is stopped. According to such a configuration, the information processing apparatus 1 can detect an incorrect simulation result when shortening the calculation time of the magnetic field simulation.

  In addition, when the maximum value of the change amount of each piece of magnetization vector data calculated for each element exceeds a predetermined amount, the information processing device 1 stops the simulation and outputs a message indicating that the simulation is stopped. According to such a configuration, the user can avoid receiving an incorrect magnetic field simulation result.

  By the way, in the first embodiment, it has been described that the magnetization change amount determination unit 54 stops the magnetic field simulation and notifies the stop when the maximum value of the change amount of each magnetization for each element is larger than the threshold value of the change amount. . However, the magnetization change amount determination unit 54 is not limited to this, and stops the magnetic field simulation when the average value of the change amount of each magnetization for each element is larger than the threshold value of the change amount, and notifies the cancellation. Is also good. In particular, when the explicit method is used in the calculation of Expression (1), the numerical value becomes unstable unless the time interval satisfies a predetermined condition. Then, the calculation of the magnetic field simulation may diverge, and the average value of the magnetization change amount may increase. In such a case, the determination based on the average value of the amount of change in magnetization in the second embodiment is effective.

  Therefore, the magnetization change amount determination unit 54 according to the second embodiment stops the magnetic field simulation when the average value of the change amount of each magnetization for each element is larger than the threshold value of the change amount, and notifies the user of the stop. explain.

[Configuration of the information processing apparatus according to the second embodiment]
The information processing apparatus 1 according to the second embodiment is the same as the information processing apparatus 1 according to the first embodiment illustrated in FIG. 1, and a description of the overlapping configuration and operation will be omitted.

[Flow chart of magnetic field simulation]
FIG. 8 is a diagram illustrating an example of a flowchart of a magnetic field simulation according to the second embodiment.

  As shown in FIG. 8, the preprocessing unit 51 generates calculation data (Step S41). For example, the preprocessing unit 51 generates the mesh data 41 used in the magnetic field simulation. The preprocessing unit 51 generates the magnetization vector data 43 used in the magnetic field simulation.

  Then, the preprocessing unit 51 sets various parameters (Step S42). For example, the preprocessing unit 51 sets an initial value of the magnetization vector data 43. The preprocessing unit 51 sets kmax, which is the maximum number of steps. The preprocessing unit 51 sets dm_max, which is a threshold value of the amount of change.

  Then, the information processing device 1 repeatedly executes the processing sandwiched between steps S43 and S47 up to the maximum number of steps kmax for each time step k. That is, the magnetic field calculation unit 52 updates the magnetic field vector including the static magnetic field vector for each element (Step S44). Then, the magnetization calculation unit 53 updates the magnetization vector for each element (Step S45). Then, the magnetization change amount determination unit 54 calculates, for each element, a change amount (magnetization change amount) of the magnetization vector between the time step k and the previous time step k-1. Then, the magnetization change amount determination unit 54 calculates the total dm_total of the magnetization change amount for the time step k from the magnetization change amount for each element. The flowchart of the magnetization change amount calculation processing will be described later.

  Then, the magnetization change amount determination unit 54 determines whether or not the average value (dm_total / imax) of the magnetization change amount is larger than the change amount threshold value dm_max (step S46). Note that dm_total is the sum of the amount of change in magnetization for each element, and imax is the maximum number of elements. It is determined whether or not the average value of the magnetization change amount is larger than the change amount threshold value dm_max (step S46). When it is determined that the average value of the magnetization change amount is equal to or smaller than the change amount threshold value dm_max (Step S46; No), the information processing device 1 proceeds to Step S43 to add 1 to the time step k. When the time step k reaches the maximum number of steps kmax, the information processing apparatus 1 ends the magnetic field simulation.

  On the other hand, when it is determined that the average value of the magnetization change amount is larger than the change amount threshold value dm_max (Step S46; Yes), the abnormal output unit 55 stops the magnetic field simulation and notifies the stop (Step S48).

[Flowchart of magnetization change amount calculation processing]
FIG. 9 is a diagram illustrating an example of a flowchart of a magnetization change amount calculation process according to the second embodiment. Note that the flowchart of FIG. 9 performs a loop for the element i at the time k, and calculates the total dm_total of the magnetization change amounts at the time k.

  As shown in FIG. 9, the magnetization change amount calculation processing initializes the total dm_total of the magnetization change amounts (step S51). The magnetization change amount calculation processing is performed on all the elements while changing i, with the processing sandwiched between steps S52 and S60 as the processing on the element i.

For each element i, the magnetic field calculator 52 updates the static magnetic field vector _{H d} (step S53). For example, the magnetic field calculator 52, the equation (9), and updates the static magnetic field vector _{H d.} Then, magnetization calculation section 53, by the equation (6), to calculate the magnetostatic energy _{E d} with a static magnetic field vector _{H d.} Then, magnetization calculation section 53 uses the magnetostatic energy E _d, and calculates the fourth term of the equation (2).

The magnetic field calculation unit 52 updates the external magnetic field vector H _app for each element i (step S54). For example, the magnetic field calculation unit 52 updates the external magnetic field vector H _app . Then, the magnetization calculation unit 53 calculates the external magnetic field energy E _app using the external magnetic field vector H _app by Expression (5). Then, the magnetization calculation unit 53 calculates the third term of Expression (2) using the external magnetic field energy H _app .

For each element i, the magnetic field calculation unit 52 updates the anisotropic magnetic field vector k (Step S55). For example, the magnetic field calculation unit 52 updates the magnetic anisotropy vector k. Then, the magnetization calculation unit 53 calculates the anisotropic energy E _ani using the magnetic anisotropy vector k by Expression (3). Then, the magnetization calculation unit 53 calculates the first term of the equation (2) using the anisotropic energy E _ani .

For each element i, the magnetic field calculation unit 52 updates the exchange coupling magnetic field vector (∇m) ² (step S56). Note that m is a magnetization vector. For example, the magnetic field calculation unit 52 updates the exchange coupling magnetic field vector (Δm) ² . Then, magnetization calculation section 53, by the equation (4), calculates the exchange coupling energy _{E exc} using an exchange coupling magnetic field vector ^{(∇m) 2.} Then, the magnetization calculation unit 53 calculates the second term of Expression (2) using the exchange coupling energy _Eexc .

For each element i, the magnetization calculation section 53 updates the magnetization vector _{m i} (step S57). For example, the magnetization calculation unit 53 calculates the effective magnetic field vector H _eff using Expression (2). Then, magnetization calculation section 53 uses the effective magnetic field vector _{H eff} calculated to calculate the equation (1), and updates the magnetization vector _{m i.}

For each element i, the magnetization change amount determination unit 54 calculates the magnetization variation dm _i (step S58). For example, the magnetization variation determining section 54 calculates the magnetization variation of the vector m _i (magnetization change amount) dm _i the time step k-1 time steps k and the previous.

Then, the magnetization change amount determination unit 54 updates the total dm_total of the magnetization change amounts (step S59). For example, the magnetization change amount determination unit 54 adds the magnetization change amount dmi for each element _i to dm_total. That is, the magnetization change amount determination unit 54 updates the total dm_total of the magnetization change amounts at the time k.

  Then, the magnetization change amount determination unit 54 ends the process after calculating the total dm_toal of the magnetization change amounts for all the elements i.

[Effect of Embodiment 2]
As described above, in the second embodiment, the information processing apparatus 1 stops the simulation when the average value of the change amounts of the respective magnetization vector data calculated for each element exceeds the predetermined amount, and informs the user of the stoppage. Is output. According to such a configuration, the user can avoid receiving an incorrect magnetic field simulation result.

  The information processing apparatus 1 can be realized by mounting the functions of the control unit 5 and the storage unit 4 on an information processing apparatus such as a known personal computer and a work station.

  In the first and second embodiments, each component of the illustrated apparatus does not necessarily need to be physically configured as illustrated. That is, the specific mode of the distribution / integration of the apparatus is not limited to the illustrated one, and all or a part of the apparatus is functionally or physically distributed / integrated in an arbitrary unit according to various loads and usage conditions. Can be configured. For example, the magnetic field calculation unit 52 and the magnetization calculation unit 53 may be integrated. The preprocessing unit 51 includes a first preprocessing unit that generates calculation data such as mesh data and magnetization vector data, and a second preprocessing unit that sets various parameters such as the initial value of the magnetization vector and the maximum number of steps. May be dispersed. The storage unit 4 may be connected as an external device of the information processing device 1 via a network.

  Further, the various processes described in the above embodiments can be realized by executing a prepared program on a computer such as a personal computer or a workstation. Therefore, an example of a computer that executes a magnetic field simulator program that realizes the same functions as the information processing device 1 illustrated in FIG. 1 will be described below. FIG. 10 is a diagram illustrating an example of a computer that executes a magnetic field simulator program.

  As illustrated in FIG. 10, the computer 200 includes a CPU 203 that performs various types of arithmetic processing, an input device 215 that receives input of data from a user, and a display control unit 207 that controls a display device 209. In addition, the computer 200 includes a drive device 213 that reads a program or the like from a storage medium, and a communication control unit 217 that exchanges data with another computer via a network. Further, the computer 200 has a memory 201 for temporarily storing various information, and an HDD (Hard Disk Drive) 205. The memory 201, CPU 203, HDD 205, display control unit 207, drive device 213, input device 215, and communication control unit 217 are connected by a bus 219.

  The drive device 213 is a device for the removable disk 211, for example. The HDD 205 stores a magnetic field simulator program 205a and magnetic field simulator related information 205b.

  The CPU 203 reads out the magnetic field simulator program 205a, expands it in the memory 201, and executes it as a process. The magnetic field simulator related information 205b corresponds to the mesh data 41, the calculation condition data 42, the magnetization vector data 43, and the magnetic field vector data 44. Then, for example, the removable disk 211 stores information such as the magnetic field simulator program 205a.

  Note that the magnetic field simulator program 205a does not necessarily need to be stored in the HDD 205 from the beginning. For example, a “portable physical medium” such as a flexible disk (FD), a CD-ROM (Compact Disk Read Only Memory), a DVD (Digital Versatile Disk), a magneto-optical disk, or an IC (Integrated Circuit) card inserted into the computer 200. The program is stored in "." Then, the computer 200 may read out the magnetization analysis program 205a from these and execute it.

REFERENCE SIGNS LIST 1 information processing device 2 input unit 3 display unit 4 storage unit 41 mesh data 42 calculation condition data 43 magnetization vector data 44 magnetic field vector data 5 control unit 51 preprocessing unit 52 magnetic field calculation unit 53 magnetization calculation unit 54 magnetization change amount determination unit 55 Error output section

Claims (5)

When simulating the state of the magnetization vector of each element obtained by dividing the magnetic material into meshes, at each time, the static magnetic field vector data of each element is approximated using the magnetization vector data,
For each element, calculate the magnetization vector data at the next time using the static magnetic field vector data at a specific time,
For each element, calculate the amount of change in the magnetization vector data between a specific time and the next time,
A magnetic field simulation program for causing a computer to execute a process of stopping the simulation based on a change amount of each of the magnetization vector data calculated for each element and outputting a message indicating that the simulation is stopped. In the output process, when the maximum value of the change amount of each of the magnetization vector data calculated for each element exceeds a predetermined amount, the simulation is stopped and a message to the effect is output. A magnetic field simulation program according to claim 1. In the output process, when the average value of the change amount of each of the magnetization vector data calculated for each element exceeds a predetermined amount, the simulation is stopped and a message to the effect is output. A magnetic field simulation program according to claim 1. When simulating the state of the magnetization vector of each element obtained by dividing the magnetic material into meshes, a magnetic field vector calculation unit that approximates the static magnetic field vector data of each element using the magnetization vector data at each time,
For each element, a magnetization calculation unit that calculates magnetization vector data at the next time using the static magnetic field vector data at a specific time,
For each element, calculate a change amount of the magnetization vector data between a specific time and the next time, and calculate a change amount;
An output unit that stops the simulation based on the amount of change in each of the magnetization vector data calculated for each element and outputs a message indicating that the simulation is stopped;
An information processing apparatus comprising: When simulating the state of the magnetization vector of each element obtained by dividing the magnetic material into meshes, at each time, the static magnetic field vector data of each element is approximated using the magnetization vector data,
For each element, calculate the magnetization vector data at the next time using the static magnetic field vector data at a specific time,
For each element, calculate the amount of change in the magnetization vector data between a specific time and the next time,
A magnetic field simulation method, comprising: performing a process of stopping the simulation based on the amount of change in each of the magnetization vector data calculated for each element and outputting a message indicating that the simulation has been stopped.

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