Classical Planar Heisenberg Ferromagnet, Complex Scalar Field and Nonlinear Excitations
Abstract
Nonlinear excitations in a classical planar Heisenberg ferromagnet in an external field (CPHFF) are studied. Taking a classical counterpart of the spinraising operator as a relevant field variable, we establish a close correspondence between the CPHFF and a complex scalar field (CSF) in which each atom in a complex lattice field, while coupled with its neighbours, sits on ψ^4like onsite potential with saturable nonlinearity; In their static form CPHFF equations and CSF equations are identical to each other. In the continuum limit the CSF takes a semiclassical form of a Bose liquid with nonlinearity, however, characteristic of classical spin system. Solutions to the field equations are studied by using the continuum approximation. In onedimensional case moving domainwall solutions associated with symmetrybreaking states are obtained for the CPHFF and the CSF. In two and threedimensional cases static solutions to the field equations are obtained in the form of vortex solutions in close analogy to the case of the GinzburgPitaevskii equation in the theory of superfluidity.
 Publication:

Progress of Theoretical Physics
 Pub Date:
 January 1981
 DOI:
 10.1143/PTP.65.172
 Bibcode:
 1981PThPh..65..172T