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TT: Fachverband Tiefe Temperaturen

TT 43: Frustrated Magnets - Strong Spin-Orbit Coupling 2 (joint session TT/MA)

TT 43.8: Vortrag

Mittwoch, 18. März 2020, 17:00–17:15, HSZ 304

Influence of spin-orbit coupling onto thermodynamic and dynamic properties of d⁵- and d⁴-systems — •Jan Lotze and Maria Daghofer — University of Stuttgart, Functional Matter and Quantum Technologies, Pfaffenwaldring 57, 70569 Stuttgart

We investigate the two-dimensional, spin-orbit coupled, three-band Hubbard model in the d⁵ and d⁴ configuration at finite temperature by means of the variational cluster approximation. Thermodynamic (magnetization, specific heat) and dynamic (DOS, spectral function) properties are presented. We investigate the influence of cluster size and symmetry on the Néel temperature T_N and on spectra.

We find that the DOS of the d⁵-system supports the picture of a system between clear Slater- and Mott-scenarios and that the orbital degrees of freedom remain quenched even for temperatures above T_N. The d⁴-system is already insulating at very high temperatures. Both a crystal field and spin-orbit coupling (SOC) lead to antiferromagnetic order at low temperature, but the finite-T properties differ markedly: Without SOC, the onsite states defining the local moments do not change substantially with T>T_N. In the presence of SOC, in contrast, weight in the onsite singlet favored by SOC increases markedly when T is lowered towards T_N. This is in agreement with X-ray reporting changes to the orbital character at temperatures above T_N.