Orbital-selective charge dynamics in $\mathrm{Y}\mathrm{Ti}{\mathrm{O}}_3$ across the magnetic transition: Combined local-density approximation and dynamical mean-field theory

The orbital-selective nature of charge dynamics in transition-metal oxides is an ill-understood phenomenon in general. Understanding its evolution across an orbital and/or magnetic phase transition promises to shed light upon the nature of ordering in strongly correlated systems. Motivated by recent work probing changes in optical absorption across the paramagnetic-ferromagnetic transition in $\mathrm{Y}\mathrm{Ti}{\mathrm{O}}_3$, we study this issue within $\mathrm{LDA}+\text{DMFT}$. We obtain good agreement with experiment, showing appreciable changes across the magnetic transition. Our study thus constitutes an attempt to address this outstanding issue and should be widely applicable to other oxides of great interest.

Figure 1

(Color online) $t_{2g}$ orbitals in the ferromagnetic state of $\mathrm{Y}\mathrm{Ti}{\mathrm{O}}_3$, as obtained within LSDA. Ground state (top/red), first excited state (middle/green), and second excited state (bottom/orange) in the projected $Pbnm$ primitive cell. The four-sublattice AFOO is clearly shown in the results (see discussion in text). The oxygens are shown in small blue spheres.

Figure 2

(Color online) L(S)DA spin- and orbital-resolved $t_{2g}$ DOSs (first three panels) for both phases: paramagnetic (Ref. 15) (dotted line) and ferromagnetic (solid line). The total DOS is shown in the last panel. All curves have been normalized to unity.

Figure 3

(Color online) $\mathrm{L}\left(\mathrm{S}\right)\mathrm{DA}+\mathrm{DMFT}$ spin- and orbital-resolved $t_{2g}$ DOSs: paramagnetic phase (Ref. 15) (dotted line, $U=5.0\mathrm{eV}$) and ferromagnetic phase (solid line, $U=4.75\mathrm{eV}$). The insets show the computed orbital-resolved and total optical conductivities for the PI (Ref. 15) (dotted) and FI (solid) phases. In the FI phase, only the majority channel is shown.