PHASE TRANSITION IN THE HEISENBERG FULLY-FRUSTRATED SIMPLE CUBIC LATTICE

The phase transition in frustrated spin systems is a fascinating subject in statistical physics. We show the result obtained by the Wang–Landau flat histogram Monte Carlo simulation on the phase transition in the fully frustrated simple cubic lattice with the Heisenberg spin model. The degeneracy of the ground state of this system is infinite with two continuous parameters. We find a clear first-order transition in contradiction with previous studies which have shown a second-order transition with unusual critical properties. The robustness of our calculations allows us to conclude this issue putting an end to the 20-year long uncertainty.

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Nematic order in a simple-cubic lattice-spin model with full-ranged dipolar interactions

Physical Review E ◽

10.1103/physreve.93.052147 ◽

2016 ◽

Vol 93 (5) ◽

Cited By ~ 3

Author(s):

Hassan Chamati ◽

Silvano Romano

Keyword(s):

Spin Model ◽

Dipolar Interactions ◽

Nematic Order ◽

Cubic Lattice ◽

Simple Cubic ◽

Simple Cubic Lattice ◽

Lattice Spin

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Skyrmions and Spin Waves in Magneto–Ferroelectric Superlattices

Entropy ◽

10.3390/e22080862 ◽

2020 ◽

Vol 22 (8) ◽

pp. 862

Author(s):

Ildus F. Sharafullin ◽

Hung T. Diep

Keyword(s):

Magnetic Field ◽

Phase Transition ◽

Triangular Lattice ◽

Applied Field ◽

Zero Field ◽

Ferroelectric Films ◽

Dm Interaction ◽

Cubic Lattice ◽

Simple Cubic ◽

Simple Cubic Lattice

We present in this paper the effects of Dzyaloshinskii–Moriya (DM) magneto–electric coupling between ferroelectric and magnetic interface atomic layers in a superlattice formed by alternate magnetic and ferroelectric films. We consider two cases: magnetic and ferroelectric films have the simple cubic lattice and the triangular lattice. In the two cases, magnetic films have Heisenberg spins interacting with each other via an exchange J and a DM interaction with the ferroelectric interface. The electrical polarizations of ±1 are assumed for the ferroelectric films. We determine the ground-state (GS) spin configuration in the magnetic film and study the phase transition in each case. In the simple cubic lattice case, in zero field, the GS is periodically non collinear (helical structure) and in an applied field H perpendicular to the layers, it shows the existence of skyrmions at the interface. Using the Green’s function method we study the spin waves (SW) excited in a monolayer and also in a bilayer sandwiched between ferroelectric films, in zero field. We show that the DM interaction strongly affects the long-wave length SW mode. We calculate also the magnetization at low temperatures. We use next Monte Carlo simulations to calculate various physical quantities at finite temperatures such as the critical temperature, the layer magnetization and the layer polarization, as functions of the magneto–electric DM coupling and the applied magnetic field. Phase transition to the disordered phase is studied. In the case of the triangular lattice, we show the formation of skyrmions even in zero field and a skyrmion crystal in an applied field when the interface coupling between the ferroelectric film and the ferromagnetic film is rather strong. The skyrmion crystal is stable in a large region of the external magnetic field. The phase transition is studied.

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