A Coherent-State Representation of the Ground State of Quantum Antiferromagnets

  • G. G. Cabrera

Abstract

The ground state of low-dimensional antiferromagnets deviates from Néel states due to strong quantum fluctuations. Exact numerical calculations in finite anisotropic chains suggest that fluctuations, in the anisotropic regime, appear in the form of localized reversal of neighboring spins. Following the above picture, we have developed a theory of antiferromagnetism that can be solved in closed analytical form through a bosonization of the Heisenberg-Ising Hamiltonian. Within the above approach, the ground state is represented as a coherent quantum wave packet with long range order, but with admixtures that include quantum fluctuations and reduce the magnetic moment from its saturation value. The theory can be extended to arbitrary spin and dimensionality, but our discussion will be restricted here to spin-1/2 and one and two dimensions. Recent developments include approximate solutions for the triangular lattice, application of external magnetic fields, and the study of doped antiferromagnets.

Keywords

Anisotropy Manifold Bors sinO 

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Copyright information

© Springer Science+Business Media New York 1994

Authors and Affiliations

  • G. G. Cabrera
    • 1
  1. 1.Instituto de Física “Gleb Wataghin”Universidade Estadual de Campinas (UNICAMP)CampinasBrazil

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