Phase Diagram of a Generalized XY Model with Geometrical Frustration

M. Lach, M. Žukovič Institute of Physics, Faculty of Science, P.J. Šafárik University, Park Angelinum 9, 041 54 Košice, Slovakia

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In the present study we investigate the effects of geometrical frustration on the XY model with antiferromagnetic coupling on a triangular lattice, generalized by the inclusion of a third-order antinematic term. We demonstrate that at non-zero temperatures such a generalization leads to a phase diagram consisting of three different quasi-long-range ordered phases. Compared to the model with the second-order antinematic coupling, it includes besides the antiferromagnetic and third-order antinematic phases which appear in the limits of relatively strong antiferromagnetic and third-order antinematic interactions, respectively, an additional complex noncollinear quasi-long-range ordered phase at lower temperatures wedged between the antiferromagnetic and third-order antinematic phases. This new phase originates from the competition between the antiferromagnetic and third-order antinematic couplings, which is absent in the model with the second-order antinematic coupling.

DOI:10.12693/APhysPolA.137.613 topics: generalized XY model, geometrical frustration, phase diagram