Fluctuation-induced first order transition due to Griffiths anomalies of the Cluster glass phase

TL;DR

This paper demonstrates that Griffiths anomalies in disordered itinerant magnetic systems induce a fluctuation-driven first-order quantum phase transition from a paramagnetic Fermi liquid to a cluster glass, with thermal effects restoring second-order behavior at higher temperatures.

Contribution

It introduces a novel mechanism where Griffiths anomalies cause a fluctuation-induced first-order transition in disordered magnetic systems.

Findings

Griffiths anomalies lead to a first-order transition at zero temperature.

Thermal effects can revert the transition to second-order.

Enhanced non-Ohmic dissipation influences the phase behavior.

Abstract

In itinerant magnetic systems with disorder, the quantum Griffiths phase at T=0 is unstable to formation of a cluster glass (CG) of frozen droplet degrees of freedom. In the absence of the fluctuations associated with these degrees of freedom, the transition from the paramagnetic Fermi liquid (PMFL) to the ordered phase proceeds via a conventional second-order quantum phase transition. However, when the Griffiths anomalies due to the broad distribution of local energy scales are included, the transition is driven first-order via a novel mechanism for a fluctuation induced first-order transition. At higher temperatures, thermal effects restore the transition to second-order. Implications of the enhanced non-Ohmic dissipation in the CG phase are briefly discussed.