TY - JOUR

T1 - Magnon spectrum and electron spin resonance in antiferromagnet with large single-ion easy plane anisotropy

AU - Sherbakov, Artemiy S.

AU - Utesov, Oleg I.

N1 - Funding Information: We are grateful to A.I. Smirnov and A.V. Syromyatnikov for stimulating discussions. The reported study was supported by the Foundation for the Advancement of Theoretical Physics and Mathematics “BASIS” Publisher Copyright: © 2020 Elsevier B.V. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2021/1/15

Y1 - 2021/1/15

N2 - Motivated by recent experiments on quantum magnet NiCl2-4SC(NH2)2 (DTN) and its Br-doped counterpart DTNX we propose a theoretical description of optical magnon branch in the antiferromagnet with large single-ion anisotropy in the magnetically ordered phase. In the framework of the 1/S expansion we derive analytical expressions for optical magnon with k=0 energy magnetic field dependence Δ(h). It is shown that in the linear spin wave approximation Δ(h) is monotonic without extrema whereas first order in 1/S corrections makes it drastically different function with a minimum near the center of magnetically ordered phase. The latter behaviour was observed in ESR experiments. Moreover, we show that Δ(h) has nontrivial dependence on the system parameters. It solves the discrepancy between inelastic neutron scattering data where the growth of interaction constants in DTNX with small Br concentration was observed and ESR experiments showing almost unchanged Δ(h) in comparison with pure DTN.

AB - Motivated by recent experiments on quantum magnet NiCl2-4SC(NH2)2 (DTN) and its Br-doped counterpart DTNX we propose a theoretical description of optical magnon branch in the antiferromagnet with large single-ion anisotropy in the magnetically ordered phase. In the framework of the 1/S expansion we derive analytical expressions for optical magnon with k=0 energy magnetic field dependence Δ(h). It is shown that in the linear spin wave approximation Δ(h) is monotonic without extrema whereas first order in 1/S corrections makes it drastically different function with a minimum near the center of magnetically ordered phase. The latter behaviour was observed in ESR experiments. Moreover, we show that Δ(h) has nontrivial dependence on the system parameters. It solves the discrepancy between inelastic neutron scattering data where the growth of interaction constants in DTNX with small Br concentration was observed and ESR experiments showing almost unchanged Δ(h) in comparison with pure DTN.

KW - Electron spin resonance

KW - Magnon spectrum

KW - Quantum corrections

KW - Quantum magnets

KW - KINEMATIC CONSISTENCY

KW - TENSOR-OPERATORS

KW - OPERATOR EXPANSIONS

KW - BOSE-EINSTEIN CONDENSATION

UR - http://www.scopus.com/inward/record.url?scp=85092102562&partnerID=8YFLogxK

U2 - 10.1016/j.jmmm.2020.167390

DO - 10.1016/j.jmmm.2020.167390

M3 - Article

AN - SCOPUS:85092102562

VL - 518

JO - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

SN - 0304-8853

M1 - 167390

ER -