Atomistic Spin Dynamics Modeling of Spintronic Control in Mn2Au

Antiferromagnetic spintronics is a complex and valuable field of ongoing research, critical for the development of beyond-start-of-the-art ultrafast, low energy computing and memory devices. Since they are largely unaffected by external magnetic fields, laser excitation, applied currents, and dynamic temperature changes represent the only methods for spintronic control in antiferromagnets. With the vast range of conducting, semi-conducting, and insulating antiferromagnets available to materials science, along with limitless multilayer combinations, there is a crucial need for advanced simulation techniques applicable to time and size scales orders of magnitude faster and smaller than ferromagnets. Mn2 Au is of high interest to the spintronics community due to the presence of an intrinsic spin-orbit torque allowing for field- free spintronic control. Likewise, Mn2 Au presents an ideal platform for advanced atomistic spin dynamics model development: a high Néel temperature, high conductivity, and ordered collinear magnetic and metallic structure make it especially appropriate for highly physical simulations with minimal compromises to model integrity. Here, we use atomistic spin dynamics to model and simulate Mn2 Au magnetic domain and domain wall control using existing and novel spintronic control methods. A chief result of this thesis is the implementation from ab initio theory of a novel laser induced torque using linearly polarised light to switch single domains and drive domain walls. The symmetry of this torque can be leveraged to produce robust toggle, preferential, and deterministic all-optical switching, even under conditions of extreme transient laser heating. This torque is also applied to domain walls, with the symmetry allowing for efficient, ultrafast domain wall motion, domain wall pinning, and domain wall contraction. An additional result with our domain wall simulations is the redescription of the model Hamiltonian used for Mn2 Au in atomistic modelling. This Hamiltonian allows for calculation of the temperature-dependent anisotropy and exchange scaling for use in micromagnetic simulations. Lastly, we expand the drift-diffusion formalism for spin transport to include the current-induced spin polarisation generating the intrinsic Néel spin-orbit torque, calculating directly the correlated effect of non-linear spin accumulation through a domain wall with the intrinsic current-induced spin accumulation of Mn2 Au.