Interplay between Jahn-Teller effect and spin-orbit coupling

The Jahn-Teller effect is one of the most fundamental phenomena important not only for physics, but also for chemistry and material science. Solving the Jahn-Teller problem and taking into account strong electron correlations we show that quantum entanglement of the spin and orbital degrees of freedom via spin--orbit coupling strongly affects this effect. Depending on the number of d electrons it may quench (electronic configurations t_2g², t_2g⁴, and t_2g⁵), partially suppress (t_2g¹) or in contrast induce (t_2g³) Jahn-Teller distortions. Moreover, in certain situations, interplay between the Jahn-Teller effect and spin--orbit coupling promotes formation of the "Mexican hat" energy surface facilitating various quantum phenomena [1].

[1] S.V. Streltsov and D.I. Khomskii Phys. Rev. X 10, 031043 (2020)