Novel approach to description of quantum magnets with large singe-ion easy-plane anisotropy

Abstract

We introduce a new representation of an integer spin $S$ via bosonic operators which is useful in describing the paramagnetic phase and transitions to magnetically ordered phases in magnetic systems with large single-ion easy-plane anisotropy $D$. Considering the exchange interaction between spins as a perturbation and using the diagram technique we derive the elementary excitation spectrum and the ground state energy in the third order of the perturbation theory. In the special case of S=1 we obtain these expressions also using simpler spin representations some of which were introduced before. Comparison with results of previous numerical studies of 2D systems with S=1 demonstrates that our approach works better than other analytical methods applied before for such systems. We apply our results for the elementary excitation spectrum analysis obtained experimentally in $\mathrm{NiC}{\mathrm{l}}_2$-$4SC(\mathrm{N}{\mathrm{H}}_2{)}_2$ (DTN). It is demonstrated that a set of model parameters (exchange constants and $D$) which has been used for DTN so far describes badly the experimentally obtained spectrum. A new set of parameters is proposed using which we fit the spectrum and values of two critical fields of DTN.

15 pages, 8 figures

References in corpus (6)

• A direct measurement of the Bose-Einstein Condensation universality class in NiCl${}_2$-4SC(NH${}_2$)${}_2$ at ultra-low temperatures
• Quantum Phase Diagram and Excitations for the One-Dimensional S=1 Heisenberg Antiferromagnet with Single-Ion Anisotropy
• Quantum fluctuations and strong mass renormalization in NiCl2-4SC(NH2)2
• Spin Dynamics of $NiC{l}_2-4SC(N{H}_2{)}_2$ in the Field-Induced Ordered Phase
• Spin-1 Heisenberg antiferromagnetic chain with exchange and single-ion anisotropies
• Antiferromagnet with two coupled antiferromagnetic sublattices in a magnetic field

Cited by in corpus (15)

• Spin nematic phase in (quasi-)one-dimensional frustrated magnet in strong magnetic field
• Dynamics of a bond-disordered $S=1$ quantum magnet near $z=1$ criticality
• Magnetic excitations in the spin-1 anisotropic antiferromagnet $NiC{l}_2-4SC(N{H}_2{)}_2$
• Localized and propagating excitations in gapped phases of spin systems with bond disorder
• Ground state properties of antiferromagnetic anisotropic S=1 Heisenberg spin chains
• Theory of field-induced quantum phase transition in spin dimer system Ba${}_3$Cr${}_2$O${}_8$
• Self-consistent T-matrix approach to gap renormalization in quantum magnets with bond disorder
• Bose-Einstein Condensation of Magnons in NiCl2-4SC(NH2)2
• Magnon spectrum and electron spin resonance in antiferromagnet with large single-ion easy plane anisotropy
• Quantum magnets with large single-ion easy-plane anisotropy in transverse magnetic field
• Antiferromagnetic resonance in a spin-gap magnet with strong single-ion anisotropy
• Superconductivity in model cuprate as an S=1 pseudomagnon condensation
• Self-consistent T-matrix approach to Bose-glass in one dimension
• Magnetodipolar interaction and quasiparticles delocalization in disordered quantum magnets
• Easy-plane antiferromagnet in tilted field: gap in magnon spectrum and susceptibility