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arXiv · 2001.00190

Pseudo-spin rotation symmetry breaking by Coulomb interaction terms in spin-orbit coupled systems

Shubhajyoti Mohapatra·Avinash Singh
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Abstract

By transforming from the pure-spin-orbital ($t_{\rm 2g}$) basis to the spin-orbital entangled pseudo-spin-orbital basis, the pseudo-spin rotation symmetry of the different Coulomb interaction terms is investigated under SU(2) transformation in pseudo-spin space. While the Hubbard and density interaction terms are invariant, the Hund's coupling and pair-hopping interaction terms explicitly break pseudo-spin rotation symmetry systematically. The form of the symmetry-breaking terms obtained from the transformation of the Coulomb interaction terms accounts for the easy $x$-$y$ plane anisotropy and magnon gap for the out-of-plane mode, highlighting the importance of mixing with the nominally non-magnetic $J$=3/2 sector, and providing a physically transparent approach for investigating magnetic ordering and anisotropy effects in perovskite ($\rm Sr_2 Ir O_4$) and other $d^5$ pseudo-spin compounds.

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Shubhajyoti Mohapatra, Avinash Singh. 2020-01-01. Pseudo-spin rotation symmetry breaking by Coulomb interaction terms in spin-orbit coupled systems. https://doi.org/10.1088/1361-648x/abc400

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