Absence of a Bulk Thermodynamic Phase Transition to a Density Wave Phase in UTe2

TL;DR

High-precision thermodynamic measurements of UTe2 reveal no bulk phase transition associated with a charge density wave, suggesting the observed CDW may be confined to the surface rather than representing a bulk order.

Contribution

This study provides the first high-precision thermodynamic evidence indicating the absence of a bulk charge density wave in UTe2, challenging previous surface-sensitive STM findings.

Findings

No thermodynamic phase transition detected in elastic moduli

Bulk charge density wave likely absent in UTe2

Surface-confined CDW suggested by the data

Abstract

Competing and intertwined orders are ubiquitous in strongly correlated electron systems, such as the charge, spin, and superconducting orders in the high-Tc cuprates. Recent scanning tunneling microscopy (STM) measurements provide evidence for a charge density wave (CDW) that coexists with superconductivity in the heavy Fermion metal UTe2. This CDW persists up to at least 7.5 K and, as a CDW breaks the translational symmetry of the lattice, its disappearance is necessarily accompanied by thermodynamic phase transition. Here, we report high-precision thermodynamic measurements of the elastic moduli of UTe2. We observe no signature of a phase transition in the elastic moduli down to a level of 1 part in 10^7, strongly implying the absence of bulk CDW order in UTe2. We suggest that the CDW and associated pair density wave (PDW) observed by STM may be confined to the surface of UTe2.