Spin-Orbit Coupling and Electronic Correlations in Sr2RuO4

Abstract

We investigate the interplay of spin-orbit coupling (SOC) and electronic correlations in Sr_{2}RuO_{4} using dynamical mean-field theory. We find that SOC does not affect the correlation-induced renormalizations, which validates Hund's metal picture of ruthenates even in the presence of the sizable SOC relevant to these materials. Nonetheless, SOC is found to change significantly the electronic structure at k points where a degeneracy applies in its absence. We explain why these two observations are consistent with one another and calculate the effects of SOC on the correlated electronic structure. The magnitude of these effects is found to depend on the energy of the quasiparticle state under consideration, leading us to introduce the notion of an energy-dependent quasiparticle spin-orbit coupling λ^{*}(ω). This notion is generally applicable to all materials in which both the spin-orbit coupling and electronic correlations are sizable.

In situ strain tuning of the metal-insulator-transition of Ca2RuO4 in angle-resolved photoemission experiments

“…We thus performed DMFT calculations of the Fermi surface including SOC following the method described in ref. 40 . As shown in Fig.…”

“…Wannier-like t 2 g orbitals were constructed out of Kohn-Sham bands within the energy window [−2, 1] eV with respect to the Fermi energy. We used the full rotationally invariant Kanamori interaction with U  = 2.3 eV and J  = 0.4 eV, which successfully describes correlated phenomena of other ruthenates 40,41 . The quantum impurity problem was solved using the continuous-time hybridization-expansion Monte Carlo impurity solver as implemented in the TRIQS library.…”

“…2c, 3e) included SOC following the methods described in ref. 40 . We verified that the orbitally diagonal elements of the self-energy matrix are not affected by SOC and that the off-diagonal elements are frequency independent up to high energies and can thus be treated as a correlation enhanced SOC.…”

Momentum-resolved superconducting energy gaps of Sr 2 RuO 4 from quasiparticle interference imaging

“…Correctly representing the electron-electron interactions is then a complex challenge. On-site and inter-site Coulomb interactions are pervasive, Hund's coupling between the Ru -orbitals generates orbital selective phenomena rendering the γ-band significantly more correlated than the α:β-bands 26 , 27 , and spin-orbit coupling plays a significant role throughout 26 . Contemporary theories 18,19,20,28,29 consider various combinations of these interactions to achieve their Δ ( ) predictions, focusing on the dependence of symmetry of the predominant Δ ( ) on the interplay between them.…”

Imaginary-time matrix product state impurity solver in a real material calculation: Spin-orbit coupling in Sr2RuO4

“…However, even with current continuous-time quantum Monte Carlo (CTQMC) [18] implementations the Fermi-liquid regime (T ≤ 25 K [2,5,19]) is inaccessible [8,[13][14][15][20][21][22]. This is especially true in the presence of SOC, where CTQMC calculations have only been performed for T > 200 K [13,14,20,23]. The signproblem prohibits studying the effect of SOC on electronic correlations at and below the Fermi-liquid temperature, yet it is essential for the precise characterization of the Fermi-liquid state and the superconducting instability emerging out of it at T ∼ 1.5 K [1][2][3], making methodological progress desirable [24].…”