Tuesday, June 25, 2013

1306.5584 (Slobodan M. Radosevic et al.)

Magnon Energy Renormalization and Low-Temperature Thermodynamics of O(3)
Heisenberg Ferromagnets

Slobodan M. Radosevic, Milan R. Pantic, Milica V. Pavkov-Hrvojevic, Darko V. Kapor
We present the perturbation theory for lattice magnon fields of $D$-dimensional O(3) Heisenberg ferromagnet. The effective Hamiltonian for the lattice magnon fields is obtained starting from the effective Lagrangian, with two dominant contributions that describe magnon-magnon interactions identified as a usual gradient term for the unit vector field and a part originating in the Wess-Zumino-Witten term of effective Lagrangian. Feynman diagrams for lattice scalar fields with derivative couplings are introduced, on basis of which we investigate the influence of magnon-magnon interactions on magnon self-energy and ferromagnet free energy. We also comment appearance of spurious terms in the low-temperature series for the free energy by examining magnon-magnon interactions and internal symmetry of the effective Hamiltonian (Lagrangian).
View original: http://arxiv.org/abs/1306.5584

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