Micromagnetic modeling of the heat-assisted switching process in high anisotropy FePt granular thin films

TY - JOUR

T1 - Micromagnetic modeling of the heat-assisted switching process in high anisotropy FePt granular thin films

AU - Atkinson, Lewis J.

AU - Evans, Richard F.L.

AU - Chantrell, Roy W.

N1 - © 2020 Author(s). Published under license by AIP Publishing. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

PY - 2020/8/20

Y1 - 2020/8/20

N2 - The dynamic process of assisted magnetic switchings has been simulated to investigate the associated physics. The model uses a Voronoi construction to determine the physical structure of the nanogranular thin film recording media, the Landau-Lifshitz-Bloch equation is solved to evolve the magnetic system in time. The reduction of the magnetization is determined over a range of peak system temperatures and for a number of anisotropy values. The results show that the heat-assisted magnetic recording process is not simply magnetization reversal over a thermally reduced energy barrier. To achieve full magnetization reversal (for all anisotropies investigated), an applied field strength of at least 6 kOe is required and the peak system temperature must reach at least the Curie point (T c). When heated to T c, the magnetization associated with each grain is destroyed, which invokes the non-precessional linear reversal mode. Reversing the magnetization through this linear reversal mode is favorable, as the reversal time is two orders of magnitude smaller than that associated with precession. Under these conditions, as the temperature decreases to ambient, the magnetization recovers in the direction of the applied field, completing the reversal process. Also, the model produces results that are consistent with the concept of thermal writability; when heating the media to T c, the smaller grains require a larger field strength to reverse the magnetization.

AB - The dynamic process of assisted magnetic switchings has been simulated to investigate the associated physics. The model uses a Voronoi construction to determine the physical structure of the nanogranular thin film recording media, the Landau-Lifshitz-Bloch equation is solved to evolve the magnetic system in time. The reduction of the magnetization is determined over a range of peak system temperatures and for a number of anisotropy values. The results show that the heat-assisted magnetic recording process is not simply magnetization reversal over a thermally reduced energy barrier. To achieve full magnetization reversal (for all anisotropies investigated), an applied field strength of at least 6 kOe is required and the peak system temperature must reach at least the Curie point (T c). When heated to T c, the magnetization associated with each grain is destroyed, which invokes the non-precessional linear reversal mode. Reversing the magnetization through this linear reversal mode is favorable, as the reversal time is two orders of magnitude smaller than that associated with precession. Under these conditions, as the temperature decreases to ambient, the magnetization recovers in the direction of the applied field, completing the reversal process. Also, the model produces results that are consistent with the concept of thermal writability; when heating the media to T c, the smaller grains require a larger field strength to reverse the magnetization.

UR - http://www.scopus.com/inward/record.url?scp=85092748539&partnerID=8YFLogxK

U2 - 10.1063/1.5143120

DO - 10.1063/1.5143120

M3 - Article

AN - SCOPUS:85092748539

SN - 0021-8979

VL - 128

JO - Journal of Applied Physics

JF - Journal of Applied Physics

IS - 7

M1 - 073907

ER -