On the Topological Features of the Helical Phase Transition in MnSi

TL;DR

This paper discusses the complex topological and thermodynamic features of the helical phase transition in MnSi, highlighting its two-step nature involving a first-order transition and topological object breakdown.

Contribution

It provides a topological perspective on the phase transition in MnSi, emphasizing the two-step process and the role of topological objects like spin vortices.

Findings

Thermodynamic and kinetic extremes near transition resemble 2D systems.

Transition occurs in two steps: first order transition then topological breakdown.

Topological objects such as spin vortices are involved in the transition.

Abstract

Many decades of study have revealed very unusual properties of the helical phase transition in MnSi. This situation is briefly described and illustrated in the present note. As one will be able to see, one peculiarity is that the phase transition point in MnSi is accompanied by extremes of different thermodynamic and kinetic quantities on the high temperature side of the transition, which look similar to a property of 2D systems. The whole situation can be tentatively described as a phase transformation of the helical phase of MnSi to the paramagnetic state, which occurs in two steps, first as a first order phase transition and then following a breakdown of topological objects such as spin vortices.