Impact of Local Lattice Disorder on Spin and Orbital Orders in Ca${}_{2-x}$Sr${}_x$RuO${}_4$

Abstract

We have studied relationship between local lattice disorder, Ru 4$d$ spin-orbit interaction, and global spin/orbital orders of Ca${}_{2-x}$Sr${}_x$RuO${}_4$ in the Sr-rich and Ca-rich regions of its phase diagram by using unrestricted Hartree-Fock calculation on a $8\times 8$ RuO${}_4$ lattice model. The calculations show that the local elongation of RuO${}_6$ octahedron in an antiferromagnetic insulator Ca${}_2$RuO${}_4$ induces local orbital change with making the Mott gap narrower. On the other hand, local compression of RuO${}_6$ octahedron in a paramagnetic metal Sr${}_2$RuO${}_4$ induces global antiferromagnetic or ferromagnetic states. This result is consistent with a recent systematic $\mu$SR study by Carlo {\it et al.} which has revealed the static antiferromagnetic order at low temperature in the Sr-rich region.

14 pages, 3 figures

References in corpus (2)

• Orbital-selective Mott transitions in the degenerate Hubbard model
• Mechanism of hopping transport in disordered Mott insulators

Cited by in corpus (3)

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