A Hierarchically-Organized Phase Diagram near a Quantum Critical Point in URu2Si2

TL;DR

This study maps the complex phase diagram of URu2Si2 near a quantum critical point, revealing multiple low-temperature phases and competing orders, with implications for understanding quantum criticality in correlated materials.

Contribution

It provides the first detailed transport-based phase diagram of URu2Si2 near its quantum critical point, highlighting multiple ordered phases and their hierarchical organization.

Findings

Quantum criticality observed above 5.5 K and 38 T.

Multiple hysteretic low-temperature phases identified.

Hierarchically-organized phase diagram with competing orders.

Abstract

A comprehensive transport study, as a function of both temperature and magnetic field in continuous magnetic fields up to 45 T reveals that URu2Si2 possesses all the essential hallmarks of quantum criticality at temperatures above 5.5 K and fields around 38 T, but then collapses into multiple low temperature phases in a hierarchically-organized phase diagram as the temperature is reduced. Although certain generic features of the phase diagram are very similar to those in the cuprates and heavy fermion superconductors, the existence of multiple ordered hysteretic phases near the field-tuned quantum critical point is presently unique to URu2Si2. This finding suggests the existence of many competing order parameters separated by small energy difference in URu2Si2.