Lattice effects in spin-orbit Mott insulators
Giniyat Khaliullin
Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
In magnetic materials without orbital degeneracy, the lattice vibrations modulate the exchange parameters (leading to, e.g., spin-Peierls effect), but do preserve the spin-rotational Heisenberg symmetry of the interactions. In transition metal oxides with unquenched orbital magnetism, however, the lattice vibrations affect the very form and symmetry properties of the effective Hamiltonians. By virtue of the spin-orbit entanglement, Jahn-Teller orbital-lattice coupling in these compounds is converted into the anisotropic pseudospin-lattice interactions [1], whose form is dictated by lattice symmetry and can directly be manipulated by the external strains [2]. These interactions drive spin-nematic and structural transitions, and have a profound impact on low-energy spin and lattice dynamics [1,3]. In particular, they lead to a coherent superposition of the magnon and phonon modes – magnetoelastic waves [4], suggesting the spin-orbit Mott insulators as useful materials in the emerging field of terahertz magnonics.
In this talk, after an introduction to the family of spin-orbit entangled Mott insulators, the above points will be discussed in the context of specific model compounds.
References
1. H. Liu and G. Khaliullin, Phys. Rev. Lett. 122, 057203 (2019).
2. H.-H. Kim, et al., Nat. Commun. 13, 6674 (2022).
3. G. Khaliullin, D. Churchill, P. P. Stavropoulos, and H.-Y. Kee, Phys. Rev. Research 3, 033163 (2021).
4. H. Liu and G. Khaliullin, unpublished.