The Vollhardt crossing point at high magnetic field

TL;DR

This study investigates the behavior of the Vollhardt crossing point in MnSi under high magnetic fields, revealing it is not an invariant feature but a consequence of fluctuation effects, thus challenging its role as a phase transition marker.

Contribution

The paper provides direct measurements showing the non-invariance of the Vollhardt crossing point in MnSi at high magnetic fields, highlighting the need for further research into its phase diagram.

Findings

Vollhardt crossing points are not invariant at high magnetic fields.

Crossing points result from fluctuation maxima or minima spreading.

Further studies are necessary to understand MnSi's phase diagram.

Abstract

Direct measurements of the Vollhardt crossing point coordinates were performed making use data of dilatometric and ultrasound experiments on MnSi. As is shown the crossing points are not invariant in the extended range of magnetic field and should be viewed as a side effects of flattening and spreading out the fluctuation maxima or minima by magnetic field~\cite{Sti16}. Correspondingly the crossing point can not be identified with a characteristic feature controlling the phase transition. So further studies are needed to understand intriguing features of the phase diagram of helical itinerant magnet MnSi.