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Fizika Tverdogo Tela, 2020 Volume 62, Issue 4, Pages 610–613 (Mi ftt8455)

Phase transitions

Two-dimensional $O(n)$ models with defects of “random local anisotropy” type

A. A. Berzina, A. I. Morozovb, A. S. Sigova

a MIREA — Russian Technological University, Moscow
b Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region

Abstract: The phase diagram of two-dimensional systems with continuous symmetry of the vector order parameter containing defects of the “random local anisotropy” type is investigated. In the case of a weakly anisotropic distribution of the easy anisotropy axes in the space of the order parameter, with decreasing temperature, a smooth transition takes place from the paramagnetic phase with dynamic fluctuations of the order parameter to the Imri–Ma phase with its static fluctuations. In the case when the anisotropic distribution of the easy axes induces a global anisotropy of the “easy axis” type that exceeds a critical value, the system goes into the Ising class of universality, and a phase transition to the ordered state occurs in it at a finite temperature.

Keywords: defects of the “random local anisotropy” type, two-dimensional $O(n)$ models, phase diagram, Imri–Ma phase.

Received: 16.12.2019
Revised: 16.12.2019
Accepted: 17.12.2019

DOI: 10.21883/FTT.2020.04.49128.650


 English version:
Physics of the Solid State, 2020, 62:4, 696–699

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