Expansion of the High Field-Boosted Superconductivity in UTe2 under Pressure

Published

September 6, 2021

Author(s)

Sheng N. Ran, Shanta R. Saha, I-Lin Liu, David Graf, Johnpierre N. Paglione, Nicholas Butch

Abstract

In semiclassical theory, the effect of quantized Landau levels on the critical magnetic field that destroys superconductivity is usually ignored. However, it has been theorized that the sharply enhanced density of states that occurs in extreme magnetic fields when the chemical potential crosses the Landau levels can have a dramatic influence on the superconducting state properties^1-4. For instance, pairing can persist to fields much higher than the quasiclassical orbital upper critical field, and the transition temperature can approach the zero-field value in the extreme quantum limit^1,2,4. Because most superconductors undergo spin-singlet pairing, these effects are not realized due to paramagnetic pairbreaking limitations, but it has long been hypothesized that such effects can be realized in triplet-paired superconductors. Here we report on the pressure evolution of the superconducting phases induced by strong magnetic fields in the spin triplet superconductor UTe₂^5,6, focusing on the extreme magnetic field-boosted pairing state that occurs when fields are directed along a specific range of off-axis angles⁷. As pressure is increased, we find that the isolated high-field superconducting phase merges with the low-field phase resulting in a zero- resistance state that persists up to at least 45 T, but remains as a distinct phase that can be separated from the field-polarized magnetic phase upon further pressure increase. Our observations of anomalies that are both insensitive to background magnetism and periodic in inverse field suggest that this superconductivity is induced by Landau-quantization effects approaching the quantum limit. Demonstration of a new method of stabilizing superconductivity in extremely high fields presents opportunities in a broad class of both fundamental and applied research in quantum materials.

Citation

NPJ Quantum Materials

Volume

6

Issue

1

Pub Type

Journals

Keywords

superconductivity, Landau level, pressure, high field

Citation

Ran, S. , Saha, S. , Liu, I. , Graf, D. , Paglione, J. and Butch, N. (2021), Expansion of the High Field-Boosted Superconductivity in UTe₂ under Pressure, NPJ Quantum Materials (Accessed October 15, 2024)