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Microscopic approach to orientational order of domain walls

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Microscopic approach to orientational order of domain walls

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Título Microscopic approach to orientational order of domain walls
Autor Barci, Daniel G.
Stariolo, Daniel Adrian
Abstract We develop a fully microscopic, statistical mechanics approach to study phase transitions in Ising systems with competing interactions at different scales. Our aim is to consider orientational and positional order parameters in a unified framework. In this paper, we consider two-dimensional stripe-forming systems, where nematic, smectic, and crystal phases are possible.We introduce a nematic order parameter in a lattice, which measures orientational order of interfaces. We develop a mean-field approach that leads to a free energy, which is a function of both the magnetization (density) and the orientational (nematic) order parameters. Self-consistent equations for the order parameters are obtained and the solutions are described for a particular system, the dipolar frustrated Ising ferromagnet.We show that this system has an Ising-nematic phase at low temperatures in the square lattice, where positional order (staggered magnetization) is zero. At lower temperatures, a crystal-stripe phase may appear. In the continuum limit, the present approach connects to a Ginsburg-Landau theory, which has an isotropic-nematic phase transition with breaking of a continuous symmetry.
Contido em Physical review. B, Condensed matter and materials physics. Woodbury. Vol. 84, no. 9 (Sep. 2011), 094439, 9 p.
Assunto Cobre
Energia livre
Ferro
Filmes finos magneticos
Fisica da materia condensada
Materiais ferromagneticos
Mecânica estatística
Modelo de ising
Paredes de domínios magnéticos
Transições magnéticas
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/104531
Arquivos Descrição Formato
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