Magnons in a two dimensional transverse field XXZ model
| Autor: | Pinaki Sengupta, Keola Wierschem, Satyaki Kar |
|---|---|
| Přispěvatelé: | School of Physical and Mathematical Sciences |
| Rok vydání: | 2016 |
| Předmět: |
Physics
Quantum Physics Condensed matter physics Strongly Correlated Electrons (cond-mat.str-el) Quantum Monte Carlo Magnon FOS: Physical sciences Magnetic Phase Transitions Science::Physics [DRNTU] 01 natural sciences Square lattice 010305 fluids & plasmas Magnetic field Condensed Matter - Strongly Correlated Electrons Spin Waves Spin wave 0103 physical sciences Condensed Matter::Strongly Correlated Electrons 010306 general physics Ground state Series expansion Anisotropy Quantum Physics (quant-ph) |
| DOI: | 10.48550/arxiv.1612.06608 |
| Popis: | The 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 non-zero field, where magnon degeneracy appears as a result of restoration of an 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. Comment: 12 pages, 9 figures |
| Databáze: | OpenAIRE |
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