Spin response and magnetic absorption of Kitaev quantum liquids under an external field

Quantum spin liquids (QSL) are novel quantum many-body systems that do not order down to zero temperature and harbor topological phases with fractionalized excitations. The Kitaev QSL on a honeycomb lattice has gapped spin excitations and extremely short-ranged spin correlations due to conserved Z₂ fluxes which governs its spin response. In the linear response regime, we explore the frequency resolved spin response and magnetic absorption of Kitaev model as a function of temperature by varying the bond strengths away from the isotropic point and by applying an out-of-plane magnetic field. The evolution of the spin response reflects the interplay between itinerant majoranas and dynamical Z₂ fluxes. Our results can be measured by microwave and terahertz spectroscopies. We also make predictions of spin relaxation phenomena that can be detected by pump-probe experiment.