Flux mobility delocalization in the Kitaev spin ladder

We study the Kitaev spin-1/2 ladder, a model which exhibits self-localization due to fractionalization caused by exchange frustration. When a weak magnetic field is applied, the model is described by an effective fermionic Hamiltonian, with an additional time-reversal symmetry-breaking term. We show that this term alone is not capable of delocalizing the system but flux mobility is a prerequisite. For magnetic fields larger but comparable to the flux gap, fluxes become mobile and drive the system into a delocalized regime, featuring finite dc transport coefficients. Our findings are based on numerical techniques, exact diagonalization, and dynamical quantum typicality, from which we present results for the specific heat, the dynamical energy current correlation function, as well as the inverse participation ratio, contrasting the spin against the fermion representation.

Automated summary

The study focuses on the self-localization and possible delocalization mechanisms of the Kitaev spin-1/2 ladder model. It is found that the influence of magnetic fields on the system is achieved through flux mobility, with flux mobility being the key to entering a delocalized state.