Fast Micromagnetic Simulation of Vortex Core Motion by GPU

Micromagnetic simulation has been used to calculate magnetization distribution and dynamics in nanoscale magnetic materials. A method reducing the calculation time is needed because it requires prolonged periods for calculation. We propose a method of calculation to reduce the calculation time with a graphics processing unit (GPU). The speed with the proposed method is fifteen times faster than that with the conventional one with a CPU at maximum. Because a GPU has very fast single precision calculation units and relatively slow double precision calculation units, it is necessary to use single precision units for fast calculation with a GPU. The difference between the results of one calculation with single and double precision units is very small. However, this difference accumulates in simulations. There is a possibility the results may change due to this difference. This effect is investigated with static and dynamic simulations with a vortex structure in a nanodot. The relative differences in static and dynamic calculations are 10-6 and 0.04, respectively. These differences are sufficiently small for practical simulations. Therefore, a method with a GPU is useful to obtain micromagnetic simulations of vortex core motion.

[1]  H. Akinaga,et al.  Direct Observation of a Systematic Change of the Magnetic-Domain Structure With Temperature in 50-nm-MnAs/GaAs(001) , 2008, IEEE Transactions on Magnetics.

[2]  W. Brown,et al.  Structure and Energy of One‐Dimensional Domain Walls in Ferromagnetic Thin Films , 1965 .

[3]  Y. Kanai,et al.  Landau–Lifshitz–Gilbert Micromagnetic Analysis of Single-Pole-Type Write Head for Perpendicular Magnetic Recording Using Full-FFT Program on PC Cluster System , 2008, IEEE Transactions on Magnetics.

[4]  Jian-Gang Zhu,et al.  Micromagnetic studies of thin metallic films (invited) , 1988 .

[5]  P. Crowell,et al.  Non-Linear Dynamics of a Magnetic Vortex , 2010, IEEE Transactions on Magnetics.

[6]  R Divan,et al.  Magnetic vortex core dynamics in cylindrical ferromagnetic dots. , 2006, Physical review letters.

[7]  B. A. Ivanov,et al.  Gyrotropic mode frequency of vortex-state permalloy disks , 2004 .

[8]  C. Shir,et al.  The effect of stress relief on magnetic distributions in ion‐implanted garnet films , 1983 .

[9]  Y Suzuki,et al.  Micromagnetic understanding of current-driven domain wall motion in patterned nanowires , 2005 .

[10]  M. Dovek,et al.  Write head analysis by using a parallel micromagnetic FEM , 2005, IEEE Transactions on Magnetics.

[11]  H. Neal Bertram,et al.  Magnetization processes in ferromagnetic cubes , 1988 .

[12]  Jung-Hwan Moon,et al.  Effect of Enhanced Damping Due to Spin-Motive Force on Field-Driven Domain Wall Motion , 2010, IEEE Transactions on Magnetics.

[13]  Werner Scholz,et al.  Scalable parallel micromagnetic solvers for magnetic nanostructures , 2003 .

[14]  Jörg Raabe,et al.  Magnetization pattern of ferromagnetic nanodisks , 2000 .

[15]  Valentyn Novosad,et al.  Magnetization reversal due to vortex nucleation, displacement, and annihilation in submicron ferromagnetic dot arrays , 2001 .

[16]  K. Guslienko,et al.  Dynamic origin of vortex core switching in soft magnetic nanodots. , 2007, Physical review letters.

[17]  M.J. Donahue,et al.  Parallelizing a Micromagnetic Program for Use on Multiprocessor Shared Memory Computers , 2009, IEEE Transactions on Magnetics.

[18]  Nobuo Hayashi,et al.  Calculation of Demagnetizing Field Distribution Based on Fast Fourier Transform of Convolution , 1996 .

[19]  Teruo Ono,et al.  Current-driven resonant excitation of magnetic vortices. , 2006, Physical review letters.

[20]  Yoshinobu Nakatani,et al.  Parallel Computation of a Demagnetizing Field in a Distributed Environment , 1999 .

[21]  R. Victora.  Micromagnetic predictions for magnetization reversal in CoNi films , 1987 .

[22]  E. Torre.  Fine particle micromagnetics , 1985 .

[23]  W. Brown,et al.  One‐Dimensional Zero‐Degree Double Bloch Walls in Thin Films , 1966 .

[24]  A. Barman,et al.  Dynamics of 1-D Chains of Magnetic Vortices in Response to Local and Global Excitations , 2010, IEEE Transactions on Magnetics.

[25]  Masud Mansuripur,et al.  Parallel micromagnetic simulations using Fourier methods on a regular hexagonal lattice , 1991 .

[26]  藤澤 明信,et al.  マイクロマグネティックシミュレータの OpenMP による高速化 , 2009 .

[27]  S. W. Yuan,et al.  Fast adaptive algorithms for micromagnetics , 1992 .

[28]  Nobuo Hayashi,et al.  Volume average demagnetizing tensor of rectangular prisms , 1998 .

[29]  Teruo Ono,et al.  Electrical switching of the vortex core in a magnetic disk. , 2007, Nature materials.

[30]  A. E. Labonte,et al.  Two‐Dimensional Bloch‐Type Domain Walls in Ferromagnetic Films , 1969 .