Transport and magnetic properties in YBaCo2O5.45: Focus on the high-temperature transition

TL;DR

This study investigates the transport and magnetic properties of YBaCo2O5.45, revealing a first-order metal-insulator transition with phase coexistence and a continuous magnetic transition, highlighting complex out-of-equilibrium phenomena.

Contribution

It provides detailed insights into the distinct nature of electronic and magnetic transitions in YBaCo2O5.45, emphasizing the role of phase coexistence and disorder effects.

Findings

Observation of resistance relaxation and thermal hysteresis near the transition

Detection of positive, linear magneto-resistance linked to heterogeneity

Identification of a continuous magnetic transition via nonlinear susceptibility

Abstract

The electronic transport properties and the magnetic susceptibility were measured in detail in $YBaCo_2O_{5.45}$. Close to the so-called metal-insulator transition, strong effects of resistance relaxation, a clear thermal hysteresis and a sudden increase of the resistance noise are observed. This is likely due to the first order character of the transition and to the underlying phases coexistence. Despite these out of equilibrium features, a positive and linear magneto-resistance is also observed, possibly linked to the heterogeneity of the state. From a magnetic point of view, the paramagnetic to ordered magnetic state transition is observed using non linear susceptibilty. This transition shows the characteristics of a continuous transition, and time dependent effects can be linked with the dynamics of magnetic domains in presence of disorder. Thus, when focusing on the order of the transitions, the electronic one and the magnetic one can not be directly associated.