Dynamics of a two-dimensional quantum spin-orbital liquid: spectroscopic signatures of fermionic magnons

Quantum spin liquids research has gained increased attention due to the synthesis of novel compounds that possibly host these phases. In some of these candidates, the local Hilbert spaces display additional orbital degrees of freedom, which opens the possibility of new routes for fractionaled excitations. In this talk, we discuss the dynamical correlations of quantum spin-orbital liquid phases of an SU(2)-symmetric Kitaev honeycomb lattice model [1]. We show that its spin dynamics is exactly the density-density correlation function of S=1 fermionic magnons, which could be probed in resonant inelastic x-ray scattering experiments. This prediction is contrasted to the expected signatures in inelastic scattering experiments, which displays a mixed response of fermionic magnons as well as spin-orbital excitations. The latter has a bandwidth of broad excitations and a vison gap that is three times larger than that of the spin-1/2 Kitaev model. The relevance of our results to real materials and directions for future research are also discussed.

[1] W. M. H. Natori, J. Knolle, Phys. Rev. Lett. 125 067201