dc.contributor.authorKar, Satyaki
dc.contributor.authorWierschem, Keola
dc.contributor.authorSengupta, Pinaki
dc.identifier.citationKar, S., Wierschem, K., & Sengupta, P. (2017). Magnons in a two-dimensional transverse-field XXZ model. Physical Review B, 96(4), 045126-. doi:10.1103/PhysRevB.96.045126en_US
dc.description.abstractThe XXZ model on a square lattice in the presence of a transverse magnetic field is studied within the spin-wave theory to investigate the resulting canted antiferromagnet. The small- and large-field regimes are probed separately both for easy-axis and easy-plane scenarios which reveal an unentangled factorized ground state at an intermediate value of the field. Goldstone modes are obtained for the field-free XY antiferromagnet as well as for the isotropic antiferromagnet with field up to its saturation value. Moreover, for an easy-plane anisotropy, we find that there exists a nonzero field, where magnon degeneracy appears as a result of restoration of a U(1) sublattice symmetry and that, across that field, there occurs a magnon band crossing. For completeness, we then obtain the system phase diagram for S=1/2 via large-scale quantum Monte Carlo simulations using the stochastic series expansion technique. Our numerical method is based on a quantization of spin along the direction of the applied magnetic field and does not suffer from a sign problem, unlike comparable algorithms based on a spin quantization along the axis of anisotropy. With this formalism, we are also able to obtain powder averages of the transverse and longitudinal magnetizations, which may be useful for understanding experimental measurements on polycrystalline samples.en_US
dc.description.sponsorshipMOE (Min. of Education, S’pore)en_US
dc.format.extent11 p.en_US
dc.relation.ispartofseriesPhysical Review Ben_US
dc.rights© 2017 American Physical Society (APS). This paper was published in Physical Review B and is made available as an electronic reprint (preprint) with permission of American Physical Society (APS). The published version is available at: [http://dx.doi.org/10.1103/PhysRevB.96.045126]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.en_US
dc.subjectMagnetic Phase Transitionsen_US
dc.subjectSpin Wavesen_US
dc.titleMagnons in a two-dimensional transverse-field XXZ modelen_US
dc.typeJournal Article
dc.contributor.schoolSchool of Physical and Mathematical Sciencesen_US
dc.description.versionPublished versionen_US

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