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Green's function approach to the low temperature properties of Cs 2CuCl 4: Anisotropy effects

Rezania, H ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1140/epjb/e2011-20738-0
  3. Abstract:
  4. We have studied the effect of both axial and transverse anisotropy on the critical field and thermodynamic properties of the field induced three dimensional antiferromagnetic Heisenberg model on the frustrated hexagonal lattice for Cs 2CuCl 4 compound. The spin model is mapped to a bosonic one with the hard core repulsion constraint and the Green's function approach has been implemented to get the low energy spectrum and the corresponding thermodynamic properties. To find the critical field (B c ) we have looked for the Bose-Einstein condensation of quasi-particles (magnons) which takes place when the magnon spectrum vanishes at the ordering spiral wave vector. We have also obtained the dispersion of magnon spectrum in the critical magnetic field for each anisotropy parameter to find the spiral wave vector where the spectrum gets its minimum. The magnon energies show a linear dispersion relation close to the quantum critical point. The effect of hard core boson interaction on the single particle excitation energies leads to a temperature dependence of the magnon spectrum versus magnetic field. We have also studied the behavior of specific heat and static structure factor versus temperature and magnetic field. © 2011 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg
  5. Keywords:
  6. Anisotropy effect ; Anisotropy parameters ; Antiferromagnetic Heisenberg models ; Critical fields ; Critical magnetic field ; Field induced ; Hard-core bosons ; Hard-core repulsion ; Hexagonal lattice ; Linear dispersion relations ; Low-energy spectra ; Magnon energies ; Magnon spectrum ; Magnons ; Quantum critical points ; Quasiparticles ; Single particle excitations ; Spin models ; Spiral waves ; Static structure factors ; Temperature dependence ; Transverse anisotropy ; Anisotropy ; Antiferromagnetic materials ; Antiferromagnetism ; Bose-Einstein condensation ; Cesium ; Cesium compounds ; Copper compounds ; Dispersion (waves) ; Green's function ; Magnetic fields ; Spectroscopy ; Statistical mechanics ; Three dimensional ; Temperature
  7. Source: European Physical Journal B ; Volume 84, Issue 1 , 2011 , Pages 37-45 ; 14346028 (ISSN)
  8. URL: http://link.springer.com/article/10.1140%2Fepjb%2Fe2011-20738-0