Field-orientation-dependent spin dynamics of the Kitaev honeycomb model

The main question we address is how to probe the fractionalized excitations of a quantum spin-liquid (QSL), for example, in the Kitaev honeycomb model. From analyzing the energy spectrum and entanglement entropy, for antiferromagnetic couplings and a field along either [111], or [-110], we find a new gapless QSL phase, sandwiched between the non-Abelian Kitaev QSL and polarized phases. Rotating the field towards [001] destroys this intermediate QSL phase and results in a considerable reduction in the number of frequency modes. In certain parameter regimes, we observe a beating pattern in the local dynamical correlations, possibly observable in pump-probe experiments. Finally, we explore the field strength and orientation dependence of the longitudinal and transverse thermal conductivities of this model as a function of temperature.