Hard-core boson approach to the spin-1/2 triangular-lattice antiferromagnet Cs${}_2$CuCl${}_4$ at finite temperatures in magnetic fields higher than the saturation field

Abstract

We study the high magnetic field regime of the antiferromagnetic insulator Cs${}_2$CuCl${}_4$ by expressing the spin-1/2 operators in the relevant Heisenberg model in terms of hard-core bosons and implementing the hard-core constraint via an infinite on-site interaction. We focus on the case where the external magnetic field exceeds the saturation field $B_c\approx 8.5\mathrm{T}$ and is oriented along the crystallographic $a$ axis perpendicular to the lattice plane. Because in this case the excited states are separated by an energy gap from the ground state, we may use the self-consistent ladder approximation to take the strong correlations due to the hard-core constraint into account. In Cs${}_2$CuCl${}_4$ there are additional interactions besides the hard-core interaction which we treat in self-consistent Hartree-Fock approximation. We calculate the spectral function of the hard-core bosons from which we obtain the in-plane components of the dynamic structure factor, the magnetic susceptibility, and the specific heat. Our results for the specific heat are in good agreement with the available experimental data. We conclude that the self-consistent ladder approximation in combination with a self-consistent Hartree-Fock decoupling of the non-hard-core interactions gives an accurate description of the physical properties of gapped hard-core bosons in two dimensions at finite temperatures.

14 pages, 15 figures

References in corpus (11)

• Unusual ordered phases of highly frustrated magnets: a review
• Spinons and triplons in spatially anisotropic frustrated antiferromagnets
• Bose-Einstein Condensation of Magnons in Cs2CuCl4
• Spin Liquid Phase in Anisotropic Triangular Lattice Heisenberg Model: Exact diagonalization and density-matrix renormalization group calculations
• Ground States of Spin-1/2 Triangular Antiferromagnets in a Magnetic Field
• Possibility of Gapless Spin Liquid State by One-dimensionalization
• Ground states of a frustrated spin-1/2 antifferomagnet: Cs_2CuCl_4 in a magnetic field
• The stable phases of the Cs2CuCl4-xBrx mixed systems
• Quasiparticles of spatially anisotropic triangular antiferromagnets in a magnetic field
• Elastic constants and ultrasonic attenuation in the cone state of the frustrated antiferromagnet Cs_2CuCl_4
• Elastic constants and ultrasound attenuation in the spin-liquid phase of Cs${}_2$CuCl${}_4$

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