Quantum magnets with large single-ion easy-plane anisotropy in magnetic field |
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Authors: | A V Sizanov A V Syromyatnikov |
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Institution: | 1.Petersburg Nuclear Physics Institute,Russian Academy of Sciences,Gatchina, St. Petersburg,Russia;2.Department of Physics,St. Petersburg State University,St. Petersburg,Russia |
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Abstract: | We propose a theory describing low-temperature properties of magnets with integer spin and large single-ion easy-plane anisotropy
D in magnetic field H directed parallel to the hard axis. Considering the exchange interaction between spins as a perturbation and using the bosonic
spin representation proposed in our recent paper 1] we find thermal corrections to the elementary excitation spectrum, magnetization
and specific heat in the vicinity of the quantum critical point (QCP) H = H
c1(0) ∼ D in the first nonvanishing orders of the perturbation theory. An expression is found for the boundary of the paramagnetic
phase H
c1(T) in the H-T plane. The effective interaction between bosons is derived near the QCP. The proposed theory describes well experimental
data obtained in NiCl2-4SC(NH2)2 (DTN). |
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Keywords: | |
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