Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 13: Correlated Electrons: Method Development I
TT 13.5: Talk
Monday, March 9, 2026, 16:00–16:15, HSZ/0101
Exact t2gn super-exchange Hamiltonians for complex orbital ordering — •Amit Chauhan, Xue-Jing Zhang, and Eva Pavarini — Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
We present a general approach for studying complex orbital ordering in t2gn correlated systems. The first step consists in building exact super-exchange (SE) Hamiltonians [1-4], projected onto irreducible tensor components. The technique we adopt is suitable both for analytic and efficient numerical calculations. Next, we obtain the total energy- which includes SE, spin-orbit and crystal-field contributions- via a variational Ansatz for the many-body wavefunction. The total energy is then optimized in the chosen parametric space to find the spin and orbitally ordered ground state. Finally, SE theory is combined with DFT+DMFT calculations via an order parameter decomposition scheme. Results for paradigmatic cases are presented.
[1] X.-J. Zhang, E. Koch, E. Pavarini, PRB 105, 115104 (2022).
[2] X.-J. Zhang, E. Koch, E. Pavarini, PRB 102, 035113 (2020).
[3] X.-J. Zhang, E. Koch, E. Pavarini, PRB 106, 115110 (2022).
[4] A. Chauhan, X.-J. Zhang, E. Pavarini (in preparation).
Keywords: Orbital ordering; Spin-orbit coupling; Super-exchange; Crystal-field splitting