SKM 2023 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 21: Spin-Dependent Phenomena in 2D

MA 21.5: Vortrag

Dienstag, 28. März 2023, 16:15–16:30, HSZ 403

Characterisation of the Ising-tye 2D magnet FePS₃: A DFT+U study — Mohammad Amirabbasi and •Peter Kratzer — Faculty of Physics, University Duisburg-Essen, 47057 Duisburg, Germany

Among the 2D magnetic system that can be prepared via exfoliation, iron phosphorus trisulfide (FePS₃) excels due to its unusual Ising-type magnetic order which makes it interesting for applications in spintronic nano-devices. We carried out a computational study of the structural and magnetic properties of single-layer FePS₃ by using Density Functional Theory (DFT+U). Our findings show that the sublattice of the Fe²⁺ ions is not a perfect honeycomb; rather the nearest-neighbor Fe distances vary by 0.14 Å as a result of orbital ordering. These lattice distortions, albeit small, trigger different (ferromagnetic and antiferromagnetic) exchange couplings so that the ground state consists of ferromagnetically aligned zig-zag chains along the long Fe-Fe bonds which couple antiferromagnetically along the shorter Fe-Fe bonds of the distorted honeycomb. Within the DFT+U framework, we parameterize a spin Hamiltonian including Heisenberg, single-ion anisotropy, Dzyaloshinskii-Moriya and biquadratic interactions that allows us to calculate the critical temperature and the magnon spectrum. By comparing to prior results from neutron scattering, we conclude that it is the upper magnon branch in a doubled unit cell that has been observed in these experiments.