Transport Properties of Metallic Ruthenates: A $\mathrm{DFT}+\mathrm{DMFT}$ Investigation

We present a systematical theoretical study on the transport properties of an archetypal family of Hund’s metals, ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$, ${\mathrm{Sr}}_3{\mathrm{Ru}}_2{\mathrm{O}}_7$, ${\mathrm{SrRuO}}_3$, and ${\mathrm{CaRuO}}_3$, within the combination of first principles density functional theory and dynamical mean field theory. The agreement between theory and experiments for optical conductivity and resistivity is good, which indicates that electron-electron scattering dominates the transport of ruthenates. We demonstrate that in the single-site dynamical mean field approach the transport properties of Hund’s metals fall into the scenario of “resilient quasiparticles.” We explain why the single layered compound ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ has a relative weak correlation with respect to its siblings, which corroborates its good metallicity.

Figure 1

The optical conductivity (left panel) and the corresponding integrated spectral weight (right panel) of ruthenates from $\mathrm{DFT}+\mathrm{DMFT}$ ($T=298\mathrm{K}$) and DFT calculations. Experimental data at room temperature are taken from [45] for comparison. S113 (a), C113 (b), S214 (c), and S327 (d) denote ${\mathrm{SrRuO}}_3$, ${\mathrm{CaRuO}}_3$, ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$, and ${\mathrm{Sr}}_3{\mathrm{Ru}}_2{\mathrm{O}}_7$ respectively.

Figure 2

The resistivity of ruthenates (a) ${\mathrm{SrRuO}}_3$ and ${\mathrm{CaRuO}}_3$, (b) ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ and ${\mathrm{Sr}}_3{\mathrm{Ru}}_2{\mathrm{O}}_7$ calculated with $\mathrm{DFT}+\mathrm{DMFT}$, in comparison with the experimental measurements taken from [10, 26, 29, 30]. The error bar is estimated from self energies of the last few converged iterations.

Figure 3

The effective plasma frequency square $({\omega }_p^{*}{)}^2$ (a) and the effective quasiparticle scattering rate $1/{\tau }_{\mathrm{tr}}^{*}$ (b) extracted from the computed optical conductivity with the $\mathrm{DFT}+\mathrm{DMFT}$ method according to the formalism in Ref. [53].

Figure 4

The calculated effective mass enhancement $m_{\text{theory}}^{*}/m_{\mathrm{DFT}}=1/Z$ (a) and the effective quasiparticle scattering rate ${\mathrm{\Gamma }}^{*}=-2ZIm\mathrm{\Sigma }(0)$ (b) of different orbitals in ruthenates. The error bar is estimated from self energies of the last few converged iterations.