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Low-energy singlet excitations in spin-1/2 Heisenberg antiferromagnet on square lattice. / Aktersky, A. Yu.; Syromyatnikov, A. V.
In: Journal of Magnetism and Magnetic Materials, Vol. 405, 2016, p. 42-47.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Low-energy singlet excitations in spin-1/2 Heisenberg antiferromagnet on square lattice
AU - Aktersky, A. Yu.
AU - Syromyatnikov, A. V.
PY - 2016
Y1 - 2016
N2 - We present an approach based on a dimer expansion which describes low-energy singlet excitations (singlons) in spin-1/2 Heisenberg antiferromagnet on simple square lattice. An operator ("effective Hamiltonian") is constructed whose eigenvalues give the singlon spectrum. The "effective Hamiltonian" looks like a Hamiltonian of a spin-1/2 magnet in strong external magnetic field and it has a gapped spectrum. It is found that singlet states lie above triplet ones (magnons) in the whole Brillouin zone except in the vicinity of the point (pi, 0), where their energies are slightly smaller. Based on this finding, we suggest that a magnon decay is possible near (pi, 0) into another magnon and a singlon which may contribute to the dip of the magnon spectrum near (pi, 0) and reduce the magnon lifetime. It is pointed out that the singlon-magnon continuum may contribute to the continuum of excitations observed recently near (pi, 0). (C) 2015 Elsevier B.V. All rights reserved.
AB - We present an approach based on a dimer expansion which describes low-energy singlet excitations (singlons) in spin-1/2 Heisenberg antiferromagnet on simple square lattice. An operator ("effective Hamiltonian") is constructed whose eigenvalues give the singlon spectrum. The "effective Hamiltonian" looks like a Hamiltonian of a spin-1/2 magnet in strong external magnetic field and it has a gapped spectrum. It is found that singlet states lie above triplet ones (magnons) in the whole Brillouin zone except in the vicinity of the point (pi, 0), where their energies are slightly smaller. Based on this finding, we suggest that a magnon decay is possible near (pi, 0) into another magnon and a singlon which may contribute to the dip of the magnon spectrum near (pi, 0) and reduce the magnon lifetime. It is pointed out that the singlon-magnon continuum may contribute to the continuum of excitations observed recently near (pi, 0). (C) 2015 Elsevier B.V. All rights reserved.
KW - 2 dimension Heisenberg antiferromagnet
KW - Simple square lattice
KW - Magnon decay
KW - MAGNON DISPERSION
KW - ZERO-TEMPERATURE
KW - MODEL
KW - EXPANSIONS
KW - SYSTEMS
KW - SERIES
U2 - 10.1016/j.jmmm.2015.12.037
DO - 10.1016/j.jmmm.2015.12.037
M3 - Article
VL - 405
SP - 42
EP - 47
JO - Journal of Magnetism and Magnetic Materials
JF - Journal of Magnetism and Magnetic Materials
SN - 0304-8853
ER -
ID: 7549895