We investigate magnetic-field-induced transitions in the dynamical spin correlation functions of the Kitaev spin liquid (KSL). Using time-dependent Majorana mean-field theory, we show that in the ferromagnetic KSL, the real-space propagation of spin correlations evolves from isotropic to highly anisotropic with increasing field strength. Notably, the anisotropy emerges as a unidirectional propagation of spin correlations, whose direction is dictated by the orientation of the magnetic field relative to the underlying Kitaev bond geometry. We analyze this phase transition through both a Majorana mean-field framework and perturbative approach, and propose some experimental signatures and possible detection schemes. We further demonstrate that a similar transition occurs in the antiferromagnetic KSL, and discuss why previous studies focusing on the [111] field direction have overlooked this phenomenon, which further suggests the possibility to identify such anisotropic dynamics in candidate Kitaev materials.

Close

PrevNext

View figure in article

• Phase transitions
• Quantum spin liquid
• Spin dynamics
• Kitaev model
• Mean field theory
• Nonequilibrium Green's function