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Zapiski Nauchnykh Seminarov POMI, 1994, Volume 209, Pages 229–259
(Mi znsl5853)
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This article is cited in 1 scientific paper (total in 1 paper)
Collective excitations in the ferro- and antiferromagnetic states of the two-dimensional repulsive Hubbard model
V. N. Popova, P. A. Sevastianovb a St. Petersburg Department of V. A. Steklov Institute of Mathematics of the Russian Academy of Sciences
b St. Petersburg Institute of Precision Mechanics and Optics
Abstract:
Collective excitations in antiferromagnetic and ferromagnetic states of the two-dimensional repulsive Hubbard model are investigated both in the phase transition vicinity (Ginsburg–Landau region $|T-T_c|\ll T_c$) and in the low-temperature region $T\ll T_c$ using the functional integration region.
The collective excitation spectrum consists of one branch at $T>T_c$ and one more branch (Goldstone branch) arises at $T<T_c$. The Goldstone branch at $T\ll T_c$ in the antiferromagnetic state is calculated including the anisotropic correction term to the linear dispersion law. The value of the non-phonon branch at the zero momentum is equal to the double gap of the fermion energy $2\Delta$. All the spectrum branches in the ferromagnetic state vanish at zero momentum ($\lim_{k\to0}E(k)=0$). Bibliography: 6 titles.
Received: 28.07.1993
Citation:
V. N. Popov, P. A. Sevastianov, “Collective excitations in the ferro- and antiferromagnetic states of the two-dimensional repulsive Hubbard model”, Questions of quantum field theory and statistical physics. Part 12, Zap. Nauchn. Sem. POMI, 209, Nauka, St. Petersburg, 1994, 229–259; J. Math. Sci., 83:1 (1997), 145–164
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https://www.mathnet.ru/eng/znsl5853 https://www.mathnet.ru/eng/znsl/v209/p229
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