Spin-orbit coupling and magnetism inSr2CrO4.

With one electron in the degenerateyz,xzorbital sector, theSr2CrO4compound 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 3dtransition 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.