Stability of the skyrmion lattice near the critical temperature in cubic helimagnets

TL;DR

This paper investigates the stability of skyrmion lattices in cubic helimagnets near the critical temperature using a Landau-Ginzburg model, showing fluctuations stabilize skyrmions as equilibrium states close to criticality.

Contribution

It introduces a Landau-Ginzburg approach with fluctuations to analyze skyrmion stability, providing a comparison with previous Fourier expansion methods.

Findings

Fluctuations stabilize skyrmion lattices near the critical temperature.

Skyrmion lattices become the equilibrium state close to criticality.

The approach aligns with and extends previous computational methods.

Abstract

The phase diagram of cubic helimagnets near the critical temperature is obtained from a Landau-Ginzburg model, including fluctuations to gaussian level. The free energy is evaluated via a saddle point expansion around the local minima of the Landau-Ginzburg functional. The local minima are computed by solving the Euler-Lagrange equations with appropriate boundary conditions, preserving manifestly the full nonlinearity that is characteristic of skyrmion states. It is shown that the fluctuations stabilize the skyrmion lattice in a region of the phase diagram close to the critical temperature, where it becomes the equilibrium state. A comparison of this approach with previous computations performed with a different approach (truncated Fourier expansion of magnetic states) is given.