Electron, phonon, and magnon dispersions and optical spectrum at finite temperature of M 2 As (M=Fe, Mn, and Cr)

Andre Schleife, University of Illinois at Urbana-Champaign

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Andre Schleife, Joshua Leveillee, Ethan Shapera, Kisung Kang, Junehu Park, Tatiane Pereira dos Santos, Erick Hernandez, Brian Robinson, Yi-Ting Lee

The magnetic storage devices have been popularly used and brought the new field of the spintronic device. Recently, antiferromagnetic materials have been revisited as the new candidate for magnetic storage devices. It leads the fundamental studies, including energy dispersions and temperature dependent properties of the antiferromagnetic materials. Especially the tetragonal antiferromagnets with easy-plane magnetism attract attention due to the possibility of storing binary information. We aim to investigate the tetragonal antiferromagnetic M2As (M=Fe, Mn, and Cr) which have easy-plane magnetism through the density functional theory formalism. Most calculations are implemented by the parallelized Vienna Ab-initio​ Simulation Package successfully run in the Blue Waters to date. The energy dispersions give an insight into the energetic contributions from electron, phonon, and magnon. The ground state calculation will provide the exchange coupling parameters and the magnetocrystalline anisotropy energies. The phonon and magnon dispersions give the guidance to understand the low energy excitations in the materials and related properties such as the heat capacities. Based on the calculated magnetic structure at the finite temperature, we are going to calculate the temperature-dependent optical spectrum of antiferromagnetic M2As. This study will provide practical guidance for experimentalists to understand the contribution of elementary particles to the properties of the materials and to maximize the signal which they want to observe. We expect the project to bring a good impact on the field of antiferromagnetic metal studies and expand the realm of the first-principles study on magnetic materials by demonstrating the calculated dispersions and the related properties to predict the potential materials.