THz-induced switching antiferromagnets

Project Description

The proposed work will support part of the EPSRC-funded New Investigator Award project, EP/T027916/1, focused on theoretical modelling of THz-frequency laser driven dynamics in magnetic materials. The project, in collaboration with the high-performance computing department at STFC, uses a combination of first principles, atomistic spin dynamics and micromagnetic modelling. The first part of the project used first principles calculations to parameterise model Hamiltonians which has now been completed for bulk antiferromagnets and is on-going for layered materials, though is nearing completion. Those Hamiltonians form the basis of the studies that we will carry out in the final part of the project on terahertz and non-linear dynamics. The GPU computing time will assist in us achieving the goals of the final part of this project which are:
1. Determine the feasibility of combining heating + THz pulses to drive magnetisation reversal in Mn2Au at low energy requirements. Mn2Au has been shown to have a weak anisotropy that scales with magnetisation to approximately the 10th power. Close to the critical temperature, the anisotropy is therefore incredibly weak, and large system sizes (>1,000,000 atomic spins) are required to overcome the thermal noise.
2. To understand the changes in the magnetisation reversal time/path when coupling Mn2Au with Permalloy and to find the optimal conditions for magnetisation reversal in FM/AFM multilayer systems
3. Determine whether non-linear dynamics and switching can be driven in synthetic multilayer structures by tuning THz pump frequencies. This will involve determining the spinwave spectra of the antiferromagnetic/ferromagnetic structures that are selected and then a systematic variation of laser parameters.