Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 27: Spin currents and spin torques

MA 27.11: Vortrag

Mittwoch, 14. März 2018, 12:15–12:30, EB 407

The effect of atomically varying anisotropy and damping on spin-transfer torque switching — •Matthew Ellis, Maria Stamenova, Mario Galante, and Stefano Sanvito — School of Physics and CRANN, Trinity College, Dublin 2, Ireland

Magnetic tunnel junctions (MTJs) form the principle unit for an array of emerging spintronic devices. Of particular interest are magnetic random access memory (MRAM) devices, where binary data is stored on the relative orientation of the two ferromagnetic layers in the MTJ. Of paramount importance to the future of MRAM is developing MTJs with material properties that provide a high readability with a low write threshold. The write threshold is determined by the effective magnetic anisotropy and damping of the free ferromagnetic layer and the strength of the spin-transfer torque (STT).

In this work, a multi-scale methodology, combining ab-initio calculations of spin-transfer torque with magnetisation dynamics computed at the atomic level, is used to model the current-induced switching in an ultra-thin Fe layer. Atomic resolved properties of the magnetic anisotropy, damping and STT are employed to explore how variations of these on the atomic scale alter the switching threshold. Little non-collinearity is observed due to the high exchange coupling while the total effective anisotropy and average damping determines the switching threshold.