On the phase diagram of UGe2

TL;DR

This paper investigates the magneto-elastic mechanism behind the first order phase transition in UGe2, explaining how pressure and critical fluctuations influence the transition's nature and temperature.

Contribution

It introduces a detailed analysis of the magneto-elastic mechanism causing the first order transition in UGe2, emphasizing the role of critical fluctuations and pressure effects.

Findings

Critical temperature drops sharply near 14-15 kbar pressure.

First order transition is enhanced by increased specific heat.

Magneto-elastic effects effectively explain the transition behavior.

Abstract

The magneto-elastic mechanism of development of the first order type instability at the phase transition to the ferromagnet state in itinerant ferromagnet-superconductor UGe2 is discussed. The particular property of this material is the precipitous drop of the critical temperature at pressure increase near 14-15 kbar that drastically increases the temperature of the first order instability in respect to the critical temperature. This effect leading to transformation of the second order type transition to the first order one is determined also by the specific heat increase in the temperature interval of the development of critical fluctuations. After performing the necessary calculations and estimations using the parameters characterizing the properties of UGe2 we argue the effectiveness of this mechanism.