Origins of anisotropic transport in the electrically switchable antiferromagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>Fe</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>NbS</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math>
Sophie F. Weber, Jeffrey B. Neaton
Abstract
Recent experiments on the antiferromagnetic intercalated transition metal dichalcogenide ${\mathrm{Fe}}_{1/3}{\mathrm{NbS}}_{2}$ have demonstrated reversible resistivity switching by application of orthogonal current pulses below its magnetic ordering temperature, making ${\mathrm{Fe}}_{1/3}{\mathrm{NbS}}_{2}$ 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 ${\mathrm{Fe}}_{1/3}{\mathrm{NbS}}_{2}$, 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 antiferromagnetic domains. Our calculations indicate that the transport anisotropy of ${\mathrm{Fe}}_{1/3}{\mathrm{NbS}}_{2}$ 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.