Multiple superconducting phases in a nearly ferromagnetic system

TL;DR

This study reveals that applying pressure to UTe2 induces multiple superconducting phases and enhances its critical temperature, providing new insights into unconventional superconductivity in nearly ferromagnetic systems.

Contribution

It demonstrates pressure-induced multiple superconducting phases and record-high critical temperature in UTe2, a nearly ferromagnetic heavy fermion superconductor.

Findings

Pressure induces multiple superconducting phases in UTe2.

Superconducting critical temperature reaches nearly 3K under pressure.

Pressure enhances superconductivity and reveals a transition within the superconducting state.

Abstract

Multiple superconducting order parameters are extremely rare. Here we show that a very small pressure can induce this phenomenon in the recently discovered heavy fermion superconductor UTe2. This nearly ferromagnetic system shows several intriguing phenomena, including an extraordinary reinforcement of superconductivity in very strong magnetic fields. We find that pressure can tune the system to a more correlated state and probable magnetic order. The superconducting critical temperature is strongly enhanced, reaching almost 3K, a new record for Ce- and U-based heavy fermion superconductors. Most spectacularly under pressure we find a transition within the superconducting state, putting UTe2 among the very rare systems having multiple superconducting phases. UTe2 under pressure is a treasure trove of several of the most fascinating phenomena in unconventional superconductivity and may well be a keystone in their understanding.