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

Abstract

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).

20 pages, 8 figures

References in corpus (5)

• Spontaneous Magnon Decays
• Counting rule for Nambu-Goldstone modes in nonrelativistic systems
• Many-body Green's function theory of Heisenberg films
• Redundancies in Nambu-Goldstone Bosons
• Massive Nambu-Goldstone Bosons

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• Using quantum mechanics for calculation of different infinite sums
• Dynamics of Frenkel excitons in pentacene
• Thermodynamics of the $d$=3+1 Quantum XY Model
• Geometry of Classical Nambu-Goldstone Fields
• Exciton dynamics in different aromatic hydrocarbon systems