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arXiv · 2006.02114

Magnetic reorientation transition in a three orbital model for $\rm Ca_2 Ru O_4$ -- Interplay of spin-orbit coupling, tetragonal distortion, and Coulomb interactions

Shubhajyoti Mohapatra·Avinash Singh
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Abstract

Including the orbital off-diagonal spin and charge condensates in the self consistent determination of magnetic order within a realistic three-orbital model for the $4d^4$ compound $\rm Ca_2 Ru O_4$, reveals a host of novel features including strong and anisotropic spin-orbit coupling (SOC) renormalization, coupling of strong orbital magnetic moments to orbital fields, and a magnetic reorientation transition. Highlighting the rich interplay between orbital geometry and overlap, spin-orbit coupling, Coulomb interactions, tetragonal distortion, and staggered octahedral tilting and rotation, our investigation yields a planar antiferromagnetic (AFM) order for moderate tetragonal distortion, with easy $a-b$ plane and easy $b$ axis anisotropies, along with small canting of the dominantly $yz,xz$ orbital moments. With decreasing tetragonal distortion, we find a magnetic reorientation transition from the dominantly planar AFM order to a dominantly $c$ axis ferromagnetic (FM) order with significant $xy$ orbital moment.

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Shubhajyoti Mohapatra, Avinash Singh. 2020-06-03. Magnetic reorientation transition in a three orbital model for $\rm Ca_2 Ru O_4$ -- Interplay of spin-orbit coupling, tetragonal distortion, and Coulomb interactions. https://doi.org/10.1088/1361-648x/abacad

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