Fast Vortex Core Switching at Moderate Temperatures

Abstract

Ferromagnetic vortex core switching is investigated using micromagnetic simulations. For that the OOMMF program is used together with a temperature extension we have developed recently. This is a continuum micromagnetic approach, where the well-known Landau Lifshitz Gilbert equation (valid for zero temperature) is replaced by the Landau Lifshitz Bloch equation. In our research we simulate switching of a ferromagnetic vortex core in a at disk (diameter 200 nm, thickness 20 nm) with material parameters that resemble permalloy. Temperatures in the range 400 K to 700 K are considered. Switching itself is caused by application of a very short oscillating magnetic pulse. Parameters used resemble conditions met in the experiment: oscillation period 141 ps (equal to the peak width) and amplitude 60 mT. Surprisingly, no large temperature- or discretization dependence is found. Reasons for that are discussed.