Multiscale ab initio skyrmionics in 2D magnets – MATRICES

Magnetic skyrmions, topologically protected chiral spin structures with particle-like properties, have attracted tremendous attention due to their potential information storage and processing applications. The main focus of the community so far has been on skyrmions in bulk, ultrathin films, and multilayers. In this proposal, we focus on newly discovered two-dimensional (2D) magnets and their van der Waals heterostuctures. First, we will employ a combined noncollinear density functional theory and atomistic spin dynamics simulations to obtain optimal heterostuctures that offer great potential for hosting skyrmions in 2D magnets. In particular, we will provide a deeper understanding of the interplay between the Dzyaloshinskii-Moriya interaction (DMI) and higher-order exchange interactions (HOI) for the skyrmion stability in these systems. The selected optimal skyrmion systems will be sandwiched between two nonmagnetic electrodes to form planar tunneling junctions, a technologically promising way for all-electrical detection of skyrmions. For this purpose, we will develop a large-scale ab initio spin-orbit transport modelling platform that enables us to model realistic quantum transport through skyrmions. This will be done by implementing two unique methods within nonequilibrium Green’s functions (NEGF) to improve the computational costs significantly. The first one is the orbital projection method that substantially reduces the Hamiltonian size. The second one is the real-space self-energy method, which removes all periodic boundary conditions. The tunneling anisotropic magnetoresistance and noncollinear magnetoresistances will be evaluated by NEGF, going far beyond the often used and less reliable Tersoff-Hamann approximation. Finally, we will study the current-induced spin-orbit torque at the 2D magnets heterostuctures. We will also explore how the DMI and HOI are modified by nonequilibrium spin currents excited by in-plane charge current, determining new means for the energy-efficient electrical control of skyrmions.