Spin–orbit coupling and magnetism in Sr2CrO4

Abstract

With one electron in the degenerate yz,xz orbital sector, the Sr2CrO4 compound exhibits active orbital degree of freedom, resulting in strongly enhanced orbital and spin-orbital correlations due to Coulomb interaction induced renormalization of the otherwise weak bare spin-orbit coupling (SOC) in this 3d transition metal compound. Finite temperature orbital fluctuations strongly reduce spin-orbital correlations, effective SOC strength, and magnon excitation energy. Orbital and magnetic transition temperatures estimated from the calculated orbiton and (renormalized) magnon energies are in good agreement with the experimental values obtained from susceptibility and resistivity anomalies in recent high-pressure studies.

Spin–orbit coupling, orbitally entangled antiferromagnetic order, and collective spin–orbital excitations in Sr2VO4

“…We will use the generalized self-consistent approach in which all orbital diagonal and orbital mixing condensates (⟨ψ † µ σψ ν ⟩ and ⟨ψ † µ ψ ν ⟩) of the spin and charge operators are included in the HF approximation of the Coulomb interaction terms. This approach was recently applied to the NaOsO 3 , Ca 2 RuO 4 , and Sr 2 IrO 4 compounds [17,21,22], and has been extended to the chromate compound Sr 2 CrO 4 [23], where a SOC induced staggered-to-entangled orbital order transition was found in the reversed crystal field regime corresponding to ambient pressure.…”