Role of Majorana fermions in spin transport of anisotropic Kitaev model

We study a quantum spin Kitaev model with zigzag edges to clarify the effects of anisotropy in the exchange couplings on spin propagation. We simulate the spin and Majorana dynamics triggered by a magnetic pulse, using the real-space time-dependent Majorana mean-field theory. When the anisotropy is small, the dispersion of the itinerant Majorana fermions remains gapless, where the velocity of the spin propagation matches the group velocity of the itinerant Majorana fermions at the nodal points. On the other hand, in the gapped system with large anisotropy, the spin propagation is strongly suppressed although its nature depends on the shape of the pulse. The spin transport in the junction system described by the Kitaev models with distinct anisotropies is also addressed.

Automated summary

In this study, the impact of anisotropy on spin propagation in a quantum spin Kitaev model with zigzag edges was investigated. It was found that for small anisotropy, the spin propagation velocity matches the group velocity of itinerant Majorana fermions, while in a gapped system with large anisotropy, spin propagation is strongly suppressed. The study also addressed spin transport in junction systems described by Kitaev models with different anisotropies.