Proposal of a micromagnetic standard problem for ferromagnetic resonance simulations

Alexander Baker, Marijan Beg, Gregory Ashton, Maximilian Albert, Dmitri Chernyshenko, Weiwei Wang, Shilei Zhang, Marc-Antonio Bisotti, Matteo Franchin, Chun Lian Hu, Robert Stamps, Thorsten Hesjedal, and Hans Fangohr ∗ Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom Faculty of Engineering and the Environment, University of Southampton, SO17 1BJ, Southampton, United Kingdom Department of Physics, Ningbo University, Ningbo 315211, China SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom Abstract Nowadays, micromagnetic simulations are a common tool for studying a wide range of different magnetic phenomena, including the ferromagnetic resonance. A technique for evaluating reliability and validity of different micromagnetic simulation tools is the simulation of proposed standard problems. We propose a new standard problem by providing a detailed specification and analysis of a sufficiently simple problem. By analyzing the magnetization dynamics in a thin permalloy square sample, triggered by a well defined excitation, we obtain the ferromagnetic resonance spectrum and identify the resonance modes via Fourier transform. Simulations are performed using both finite difference and finite element numerical methods, with OOMMF and Nmag simulators, respectively. We report the effects of initial conditions and simulation parameters on the character of the observed resonance modes for this standard problem. We provide detailed instructions and code to assist in using the results for evaluation of new simulator tools, and to help with numerical calculation of ferromagnetic resonance spectra and modes in general.