Defect-Mediated Melting of Square-Lattice Solids

Fuente: arXiv
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Autori principali: Grampel, William, Podolsky, Daniel
Natura: Preprint
Pubblicazione: 2025
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author Grampel, William
Podolsky, Daniel
author_facet Grampel, William
Podolsky, Daniel
contents The Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory successfully explains the melting mechanism of two-dimensional isotropic lattices as a two-step process driven by the unbinding of topological defects. By considering the elastic theory of the square lattice, we extend the KTHNY theory to melting of square lattice solids. In addition to the familiar elastic constants that govern the theory -- the Young's modulus and the Poisson ratio -- a third constant controlling the anisotropy of the medium emerges. This modifies both the logarithmic and angular interactions between the topological defects. Despite this modification, the extended theory retains the qualitative features of the isotropic case, predicting a two-step melting with an intermediate tetratic phase. However, some subtle differences arise, including a modified bound on the translational correlation exponent and the absence of universal values for the Young's modulus at the solid-to-tetratic phase transition.
format Preprint
id arxiv_https___arxiv_org_abs_2507_16418
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Defect-Mediated Melting of Square-Lattice Solids
Grampel, William
Podolsky, Daniel
Soft Condensed Matter
Materials Science
Statistical Mechanics
The Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory successfully explains the melting mechanism of two-dimensional isotropic lattices as a two-step process driven by the unbinding of topological defects. By considering the elastic theory of the square lattice, we extend the KTHNY theory to melting of square lattice solids. In addition to the familiar elastic constants that govern the theory -- the Young's modulus and the Poisson ratio -- a third constant controlling the anisotropy of the medium emerges. This modifies both the logarithmic and angular interactions between the topological defects. Despite this modification, the extended theory retains the qualitative features of the isotropic case, predicting a two-step melting with an intermediate tetratic phase. However, some subtle differences arise, including a modified bound on the translational correlation exponent and the absence of universal values for the Young's modulus at the solid-to-tetratic phase transition.
title Defect-Mediated Melting of Square-Lattice Solids
topic Soft Condensed Matter
Materials Science
Statistical Mechanics
url https://arxiv.org/abs/2507.16418