TY  - JOUR
AU  - Zhang, Guoren
AU  - Pavarini, Eva
TI  - Higgs mode and stability of x y -orbital ordering in Ca 2 RuO 4
JO  - Physical review / B
VL  - 101
IS  - 20
SN  - 2469-9950
CY  - Woodbury, NY
M1  - FZJ-2020-03812
SP  - 205128
PY  - 2020
AB  - 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 $Ca_{2}RuO_{4}$.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1103/PhysRevB.101.205128
UR  - https://juser.fz-juelich.de/record/885415
ER  -