Absence of orbital-selective Mott transition in Ca_2-xSr_xRuO4

TL;DR

This study uses Dynamical Mean Field Theory to analyze the electronic spectra of Sr$_2$RuO$_4$ as Coulomb interactions increase, finding no orbital-selective Mott transition but a simultaneous transition for all bands.

Contribution

It demonstrates that, contrary to some expectations, all $t_{2g}$ bands undergo a collective metal-insulator transition without orbital selectivity in Ca$_{2-x}$Sr$_x$RuO$_4$.

Findings

Spectral features of $t_{2g}$ bands become similar at high $U$

No evidence of orbital-selective Mott transition

All bands transition simultaneously at the same critical $U$

Abstract

Quasi-particle spectra of the layer perovskite Sr$_2$RuO$_4$ are calculated within Dynamical Mean Field Theory for increasing values of the on-site Coulomb energy $U$. At small $U$ the planar geometry splits the $t_{2g}$ bands near $E_F$ into a wide, two-dimensional $d_{xy}$ band and two narrow, nearly one-dimensional $d_{xz,yz}$ bands. At larger $U$, however, the spectral distribution of these states exhibit similar correlation features, suggesting a common metal-insulator transition for all $t_{2g}$ bands at the same critical $U$.