Soluções não homogeneas das equações de Ginzburg-Landau em antiferromagnetos dopados

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

We propose a phenomenological model based on the Ginzburg-Landau theory of phase transitions, that describes the thermodynamic behavior of charge and spin density waves present in high-Tc doped antiferromagnets. One of the current ideas, supported by recent neutron scattering measurements, is that doping introduces charge excess that accumulates on the antiferromagnetic Cu - O planes, leading to a nonhomogeneous incommensurable phase of charged stripes. The Landau functional is constructed based on symmetry arguments, and we find a stripe commensurability transition that separates the low temperature incompressible phase from the high incommensurable one. Modeling the problem with a single order parameter for the staggered magnetization, leads to a soliton - like static charge distribution in the regime of low doping and temperature. In this region of the phase diagram, the charge strongly segregates into the Néel walls that appear between antiferromagnetic domains, producing charge density peaks whose amplitude is almost independent on doping concentration. Next, we introduce a second order parameter directly related to the charge distribution in the high temperature phase. By raising the temperature one delocalize this distribution. The solution obtained in this case, describes a highly incommensurable softh modulaton, in agreement with experimental observations

ASSUNTO(S)

supercondutores de alta temperatura transformações de fase (fisica estatistica)

ACESSO AO ARTIGO

Documentos Relacionados