Theoretical Solid State Physics

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Quantum Spin Liquid Ground States of the Heisenberg-Kitaev Model on the Triangular Lattice

Pavel Kos

03.11.2016 at 12:15 

We investigate quantum disordered spin liquid ground states of the Heisenberg-Kitaev model on the triangular lattice using Schwinger-boson mean-field theory. Our goal is to identify and characterize potential gapped spin liquid ground states. After reviewing known results of Heisenberg-Kitaev model, projective symmetry group (PSG) analysis is carried out to determine the possible mean-field ansatzes.
Later, we focus on the only totally symmetric ansatz and compute the mean-field parameters self-consistently. Depending on the ratio of Kitaev and Heisenberg coupling, we find three spin liquid ground states separated by two continuous phase transitions.
To characterise these phases, we compute one spinon dispersions, static spin structure factors and examine their classical limits. Close to the Heisenberg point we find SU(2) invariant zero-flux phase known from studies of the Heisenberg model on the triangular lattice.
In the opposite Kitaev-limit, a spin liquid that has the classical ground state of the Kitaev model as its classical limit is found. Interestingly, at intermediate couplings we observe a novel spin liquid ground state with non-zero couplings of different spin components.

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