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TT: Fachverband Tiefe Temperaturen

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

TT 43.7: Vortrag

Mittwoch, 18. März 2020, 16:45–17:00, HSZ 304

Excitonic Magnetism at the intersection of Spin-orbit coupling and crystal-field splitting — Teresa Feldmaier¹, Pascal Strobel¹, Michael Schmid^1,2, Philipp Hansmann³, and •Maria Daghofer¹ — ¹FMQ, Universität Stuttgart, Germany — ²IQST, Stuttgart and Ulm, Germany — ³MPI-CPfS, Dresden, Germany

Excitonic magnetism involving superpositions of singlet and triplet states is expected to arise for two holes in strongly correlated and spin-orbit coupled t_2g orbitals. However, uncontested material examples for its realization are rare. Applying the Variational Cluster Approach to the square lattice, we find for weak spin-orbit coupling stripy spin antiferromagnetism combined with stripy orbital order without a crystal field and checkerboard spin antiferromagnetism when crystal field favors the xy orbital. Strong spin-orbit coupling leads to excitonic antiferromagnetism that can coexist with substantial orbital polarization. We then address the specific example of Ca₂RuO₄ using ab initio modeling and conclude it to realize excitonic magnetism despite its pronounced orbital polarization.