Origins of anisotropic transport in electrically-switchable antiferromagnet $\mathrm{Fe_1/3NbS_2}$

TL;DR

This study uses density functional theory to analyze the electronic structure and transport properties of $ ext{Fe}_{1/3} ext{NbS}_2$, explaining the anisotropic resistivity switching observed in experiments and its relation to magnetic domain reorientation.

Contribution

It provides a theoretical understanding of the origin of resistivity switching in $ ext{Fe}_{1/3} ext{NbS}_2$ by calculating magnetic states, electronic structure, and transport anisotropy, linking them to experimental observations.

Findings

Antiferromagnetic ground states are nearly degenerate.

Transport anisotropy depends on magnetic order and Hubbard U value.

Current-induced domain stabilization explains resistivity switching.

Abstract

Recent experiments on the antiferromagnetic intercalated transition metal dichalcogenide $\mathrm{Fe_{1/3}NbS_2}$ have demonstrated reversible resistivity switching by application of orthogonal current pulses below its magnetic ordering temperature, making $\mathrm{Fe_{1/3}NbS_2}$ promising for spintronics applications. Here, we perform density functional theory calculations with Hubbard U corrections of the magnetic order, electronic structure, and transport properties of crystalline $\mathrm{Fe_{1/3}NbS_2}$, clarifying the origin of the different resistance states. The two experimentally proposed antiferromagnetic ground states, corresponding to in-plane stripe and zigzag ordering, are computed to be nearly degenerate. In-plane cross sections of the calculated Fermi surfaces are anisotropic for both magnetic orderings, with the degree of anisotropy sensitive to the Hubbard U value. The in-plane resistance, computed within the Kubo linear response formalism using a constant relaxation time approximation, is also anisotropic, supporting a hypothesis that the current-induced resistance changes are due to a repopulating of AFM domains. Our calculations indicate that the transport anisotropy of $\mathrm{Fe_{1/3}NbS_2}$ in the zigzag phase is reduced relative to stripe, consistent with the relative magnitudes of resistivity changes in experiment. Finally, our calculations reveal the likely directionality of the current-domain response, specifically, which domains are energetically stabilized for a given current direction.