Phase Diagrams of Spin-S Kitaev Ladders

We investigate the ground states of spin-S Kitaev ladders using exact analytical solutions, perturbation theory and the density matrix renormalization group (DMRG) method.

We find an even-odd effect: in the case of half-integer S, we find phases with spontaneous symmetry breaking (SSB) and symmetry-protected topological (SPT) order; for integer S, we find SSB and trivial paramagnetic phases. We also study the transitions between the various phases; notably, for half-integer S we find a transition between two distinct SPT orders, and for integer S we find unnecessary first order phase transitions within a trivial phase.