Interplay between disorder, quantum and thermal fluctuations in ferromagnetic alloys: The case of UCu2Si(2-x)Ge(x)

TL;DR

This paper investigates how disorder, quantum, and thermal fluctuations influence the magnetic and transport properties of UCu2Si(2-x)Ge(x) alloys, revealing that their Curie temperature can be enhanced through this interplay.

Contribution

It provides a combined theoretical and experimental analysis of disorder and fluctuations effects in ferromagnetic alloys, highlighting the non-monotonic behavior of Curie temperature.

Findings

Resistivity exhibits Fermi liquid behavior at low temperatures.

Residual resistivity follows disordered alloy behavior.

Curie temperature shows non-monotonic dependence on x, influenced by quantum and thermal fluctuations.

Abstract

We consider, theoretically and experimentally, the effects of structural disorder, quantum and thermal fluctuations in the magnetic and transport properties of certain ferromagnetic alloys.We study the particular case of UCu2Si(2-x)Ge(x). The low temperature resistivity, rho(T,x), exhibits Fermi liquid (FL) behavior as a function of temperature T for all values of x, which can be interpreted as a result of the magnetic scattering of the conduction electrons from the localized U spins. The residual resistivity, rho(0,x), follows the behavior of a disordered binary alloy. The observed non-monotonic dependence of the Curie temperature, Tc(x), with x can be explained within a model of localized spins interacting with an electronic bath whose transport properties cross-over from ballistic to diffusive regimes. Our results clearly show that the Curie temperature of certain alloys can be enhanced due to the interplay between quantum and thermal fluctuations with disorder.