2023/05/16 by Corrado Carlo Maria Capriata, B. Gunnar Malm, Capriata, Corrado Carlo Maria +5
Physics and Astronomy · Materials Science · #Magnetic properties of thin films #Theoretical and Computational Physics #Magnetic Properties and Applications
paper · pdf · doi:10.48550/arxiv.2305.09558
Thermally-induced transitions between bistable magnetic states of magnetic tunnel junctions (MTJ) are of interest for generating random bitstreams and for applications in stochastic computing. An applied field transverse to the easy axis of a perpendicularly magnetized MTJ (pMTJ) can lower the energy barrier (Eb) to these transitions leading to faster fluctuations. In this study, we present analytical and numerical calculations of Eb considering both coherent (macrospin) reversal and non-uniform wall-mediated magnetization reversal for a selection of nanodisk diameters and applied fields. Non-uniform reversal processes dominate for larger diameters, and our numerical calculations of Eb using the String method show that the transition state has a sigmoidal magnetization profile. The latter can be described with an analytical expression that depends on only one spatial dimension, parallel to the applied field, which is also the preferred direction of profile motion during reversal. Our results provide nanodisk energy barriers as a function of the transverse field, nanodisk diameter, and material characteristics, which are useful for designing stochastic bitstreams.