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Declining Commodity Program Payments and Enhanced Environmental Regulations: Impacts on Acreage Allocation in the Great Plains
Environmental Economics and Policy,
Spin chain in magnetic field: limitations of the large-N mean-field theory
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.Comment: 4 pages, 3 figures; appeared in the proceedings of the European
Conference "Physics of Magnetism" (2014
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