%0 Journal Article
%A Zhang, Guoren
%A Pavarini, Eva
%T Higgs mode and stability of x y -orbital ordering in Ca 2 RuO 4
%J Physical review / B
%V 101
%N 20
%@ 2469-9950
%C Woodbury, NY
%M FZJ-2020-03812
%P 205128
%D 2020
%X We investigate the stability of xy orbital ordering and the nature of the magnetic longitudinal excitations in $Ca_{2}RuO_{4}$. To this end, we employ the local-density approximation + dynamical mean-field theory approach, in combination with many-body perturbation theory. We show that the crossover to a nonperturbative spin-orbit regime—-in which xy-like orbital ordering is to a large extent quenched—only takes place when the crystal field is sizably reduced with respect to its actual value in $Ca_{2}RuO_{4}$. In the small crystal-field splitting limit, the spin-orbit interaction favors the metal-to-insulator transition. We find that the effects of the spin-orbit interaction remain perturbative even for the less distorted $Ca_{2−x}Sr_xRuO_4$ with 0< x<0,2 ($S$-Pbca phase) and for the $S^∗$ phase. We show that, nevertheless, a Higgs mode at ω∼50meV is compatible with xy-like orbital ordering in $Ca_{2}RuO_{4}$.
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1103/PhysRevB.101.205128
%U https://juser.fz-juelich.de/record/885415