Semiclassical and field theoretic studies of Heisenberg antiferromagnetic chains with frustration and dimerization

Sumathi Rao; Diptiman Sen

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arXiv · cond-mat/9604044

Semiclassical and field theoretic studies of Heisenberg antiferromagnetic chains with frustration and dimerization

Sumathi Rao·Diptiman Sen

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Abstract

The Heisenberg antiferromagnetic spin chain with both dimerization and frustration is studied. The classical ground state has three phases (a Neel phase, a spiral phase and a colinear phase), around which a planar spin-wave analysis is performed. In each phase, we discuss a non-linear sigma model field theory describing the low energy excitations. A renormalization group analysis of the SO(3) matrix-valued field theory of the spiral phase leads to the conclusion that the theory becomes $SO(3) \times SO(3)$ and Lorentz invariant at long distances. This theory is analytically known to have a massive spin-1/2 excitation. We also show that $Z_2 ~$ solitons in the field theory lead to a double degeneracy in the spectrum for half-integer spins.

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Sumathi Rao, Diptiman Sen. 1996-04-09. Semiclassical and field theoretic studies of Heisenberg antiferromagnetic chains with frustration and dimerization. https://arxiv.org/abs/cond-mat/9604044

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