Effects of exchange and weak Dzyaloshinsky-Moriya anisotropies on thermodynamic characteristics of spin-gapped magnets

Abstract

We study the modification of low temperature properties of quantum magnets such as magnetization, heat capacity, energy spectrum, and densities of condensed and noncondensed quasiparticles (triplons) due to anisotropies in the framework of mean-field based approach. We show that in contrast to exchange anisotropy (EA) interaction, Dzyaloshinsky-Moriya (DM) interaction modifies the physics dramatically. Particularly, it changes the sign of the anomalous density in the whole range of temperatures. Its critical behavior is slightly modified also by the EA. We have found that the shift of the critical temperature of phase transition (or crossover caused by DM interaction) is positive and significant. Using the experimental data on the magnetization of the compound TlCuCl${}_3$, we have found optimal values for the strengths of EA and DM interactions. The spectrum of the energy of low lying excitations has also been investigated and found to develop a linear dispersion similar to Goldstone mode with a negligibly small anisotropy gap.

25 pages, 18 figures

References in corpus (11)

• Quantum depletion of a homogeneous Bose-Einstein condensate
• Spin-resonance modes of the spin-gap magnet TlCuCl_3
• Bose-Einstein Condensation of Magnons in TlCuCl3: Phase diagram and specific heat from a self-consistent Hartee-Fock calculation with a realistic dispersion relation
• Consequences of spin-orbit coupling for the Bose-Einstein condensation of magnons
• Bose-Einstein condensation temperature of weakly interacting atoms
• Particle-hole symmetry breaking in a spin-dimer system TlCuCl${}_3$ observed at 100 T
• Stability of the homogeneous Bose-Einstein condensate at large gas parameter
• The fraction of Bose-Einstein condensed triplons in TlCuCl3 from magnetization M(T,H)-data
• Gr{ü}neisen parameter of quantum magnets with spin gap
• Spin-gapped magnets with weak anisotropies I: Constraints on the phase of the condensate wave function
• Characteristic temperatures of a triplon system of dimerized quantum magnets

Cited by in corpus (4)

• Self-consistent theory of a homogeneous binary Bose mixture with strong repulsive interspecies interaction
• On the anomalous density of a dilute homogeneous Bose gas
• Hugenholtz -- Pines relations and the critical temperature of a Rabi coupled binary Bose system
• Defining a critical temperature of a crossover from BEC to the normal phase in anisotropic quantum magnets