Quasi-uniaxial pressure induced superconductivity in stoichiometric compound UTe$_2$

TL;DR

This study demonstrates that stoichiometric UTe2 is non-superconducting at ambient and hydrostatic pressures but becomes superconducting under quasi-uniaxial pressure, revealing the importance of directional stress and Te deficiency.

Contribution

First to show that quasi-uniaxial pressure induces superconductivity in stoichiometric UTe2, clarifying the role of pressure direction and composition in its superconducting properties.

Findings

Superconductivity emerges at 1.5 GPa under quasi-uniaxial pressure.

Superconductivity develops in three crystallographic directions at 4.8 GPa.

Superconductivity coexists with an exotic magnetic ordered state.

Abstract

The recent discovery of superconductivity in heavy Fermion compound UTe2, a candidate topological and triplet-paired superconductor, has aroused widespread interest. However, to date, there is no consensus on whether the stoichiometric sample of UTe2 is superconducting or not due to lack of reliable evidence to distinguish the difference between the nominal and real compositions of samples. Here, we are the first to clarify that the stoichiometric UT2 is non-superconducting at ambient pressure and under hydrostatic pressure up to 6 GPa, however we find that it can be compressed into superconductivity by application of quasi-uniaxial pressure. Measurements of resistivity, magnetoresistance and susceptibility reveal that the quasi-uniaxial pressure results in a suppression of the Kondo coherent state seen at ambient pressure, and then leads to a superconductivity initially emerged on the ab-plane at 1.5 GPa. At 4.8 GPa, the superconductivity is developed in three crystallographic directions. The superconducting state coexists with an exotic magnetic ordered state that develops just below the onset temperature of the superconducting transition. The discovery of the quasi-uniaxial-pressure-induced superconductivity with exotic magnetic state in the stoichiometric UTe2 not only provide new understandings on this compound, but also highlight the vital role of Te deficiency in developing the superconductivity at ambient pressures.