On phase separation in the generalised spherical model

Angelescu, N; Bundaru, M; Costache, G.

doi:10.1088/0305-4470/14/12/010

Cited by 6 publications

(2 citation statements)

References 12 publications

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“…For the D-vector model the separation of a specimen into domains with opposite magnetizations by domain walls of a finite width requires an easy-axis anisotropy, which makes the intermediate orientation of the magnetization in the wall energetically unfavourable in comparison to that in domains. Clearly, this actual situation cannot be treated either with the help of the spherical model in its standard formulation [1], or with the improved version [11,19], which is equivalent to the isotropic D = ∞ model in the general inhomogeneous case.…”

Section: Introductionmentioning

confidence: 99%

Bloch-wall phase transition in the spherical model

Garanin

1996

J. Phys. A: Math. Gen.

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The temperature-induced second-order phase transition from Bloch to linear (Ising-like) domain walls in uniaxial ferromagnets is investigated for the model of D-component classical spin vectors in the limit D → ∞. This exactly soluble model is equivalent to the standard spherical model in the homogeneous case, but deviates from it and is free from unphysical behavior in a general inhomogeneous situation. It is shown that the thermal fluctuations of the transverse magnetization in the wall (the Bloch-wall order parameter) result in the diminishing of the wall transition temperature TB in comparison to its mean-field value, thus favouring the existence of linear walls. For finite values of TB an additional anisotropy in the basis plane x, y is required; in purely uniaxial ferromagnets a domain wall behaves like a 2-dimensional system with a continuous spin symmetry and does not order into the Bloch one. †

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Section: Introductionmentioning

confidence: 99%

Bloch-wall phase transition in the spherical model

Garanin

1996

J. Phys. A: Math. Gen.

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“…It is clear that the anisotropy is an important characteristic of the model, giving rise to the very existence of domain walls of finite width separating the "up" and "down" domains. For this reason, the attempts to describe domain walls with the traditional SM in both versions with [45] and without [46] the global spin constraint could not yield relevant results.…”

Section: Introductionmentioning

confidence: 99%

Semi-infinite anisotropic spherical model: Correlations atT>~Tc

Garanin

1998

Phys. Rev. E

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The ordinary surface magnetic phase transition is studied for the exactly solvable anisotropic spherical model ͑ASM͒, which is the limit D→ϱ of the D-component uniaxially anisotropic classical vector model. The bulk limit of the ASM is similar to that of the spherical model, apart from the role of the anisotropy stabilizing ordering for low lattice dimensions, dр2, at finite temperatures. The correlation functions and the energy density profile in the semi-infinite ASM are calculated analytically and numerically for TуT c and 1рdрϱ. Since the lattice dimensionalities dϭ1, 2, 3, and 4 are special, a continuous spatial dimensionality dЈϭd Ϫ1 has been introduced for dimensions parallel to the surface. However, preserving a discrete layer structure perpendicular to the surface avoids unphysical surface singularities and allows numerical solitions that reveal significant short-range features near the surface. The results obtained generalize the isotropic-criticality results for 2ϽdϽ4 of Bray and Moore ͓Phys.

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