paper

Spin chain in magnetic field: limitations of the large-N mean-field theory

arXiv:1504.00996 · doi:10.12693/APhysPolA.127.201

Abstract

Motivated by the recent success in describing the spin and orbital spectrum of a spin-orbital chain using a large-N mean-field approximation [Phys. Rev. B 91, 165102 (2015)], we apply the same formalism to the case of a spin chain in the external magnetic field. It occurs that in this case, which corresponds to N=2 in the approximation, the large-N mean-field theory cannot qualitatively reproduce the spin excitation spectra at high magnetic fields, which polarize more than 50% of the spins in the magnetic ground state. This, rather counterintuitively, shows that the physics of a spin chain can under some circumstances be regarded as more complex than the physics of a spin-orbital chain.

arXiv comment4 pages, 3 figures; appeared in the proceedings of the European Conference "Physics of Magnetism" (2014)

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