Spin Models With Different Types of Competing Interactions

Abstract

We consider a spin-glass model with an arbitrary range of competing interactions within two-particle cluster approximation for the free energy and within symmetric replica approach. We show that for the thermodynamic characteristics, the Gaussian approximation for distribution functions of cluster (short-range) fields can be used. For a simple proton-glass model with weak long-range interactions (linear approximation) we study the influence of the long-range interactions and random internal fields on the phase diagram and thermodynamics characteristics. It is shown that small fluctuations of internal fields can lead to essential smearing of spin-glass transition region.

Thermodynamics and complex dielectric permittivity of mixed crystals of the Rb_{1-x}(NH_{4})_{x}H_{2}PO_{4} type

“…From equations (42), (43) we derive expressions forφ (ω),q (ω) used to findη f f (ω) (40). For the sake of simplicity, in what follows we shall use an effective relaxation timeτ 0…”

“…In [40,41] a theory of static properties of model proton glasses with an arbitrary range of competing interactions was proposed. Thermodynamic properties of the model with essential short-range and weak long-range interactions were explored within the two-particle cluster approximation.…”

“…Thermodynamic properties of the model with essential short-range and weak long-range interactions were explored within the two-particle cluster approximation. In the present paper, the approaches developed in [39][40][41] are used to describe thermodynamic and dielectric properties of hydrogen bonded…”

Thermodynamics, dielectric permittivity and phase diagrams of the Rb_{1-x}(NH_{4})_{x}H_{2}PO_{4} type proton glasses

“…In [78][79][80][81] a theory of static characteristics of model proton glasses with an arbitrary range of competing interactions has been proposed. In [82,83] a similar approach has been used for the description of some thermodynamic characteristics and transverse dielectric permittivity of hydrogen bonded Rb 1−x (ND 4 ) x D 2 PO 4 and Rb 1−x (NH 4 ) x H 2 AsO 4 compounds, in which an essential role in the formation of energy levels is played by the proton short-range correlations.…”

Monte Carlo study of the honeycomb structure of anthraquinone molecules on Cu(111)

“…They can be a 2D dipolar lattice gas, 15 a 2D dipolar Ising model without vacancies [16][17][18][19][20][21] and with random vacancies, 22 a 2D frustrated system, 23 a bidimensional fluid system, 24 a 2D quantum Heisenberg model, 25 a density anomaly, 26 a spin-glass state, 27 correlations in fluids, 28 compositional patterns on bulk-immiscible alloy films, 29 and a colloidal fluid. 30 Our work is also based on this method.…”