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Single-Component Superconductivity in UTe2 at Ambient Pressure



Florian Theuss, Avi Shragai, Gael Grissonnanche, Ian Hayes, Shanta Saha, Yun Eo, Alonso Suarez, Tatsuya Shishidou, Nicholas Butch, Johnpierre Paglione, B. Ramshaw


The microscopic mechanism of Cooper pairing in a superconductor leaves its fingerprint on the symmetry of the order parameter. UTe2 has been inferred to have a multi-component order parameter that entails exotic effects like time reversal symmetry breaking. However, recent experimental observations in newer-generation samples have raised questions about this interpretation, pointing to the need for a direct experimental probe of the order parameter symmetry. Here, we use pulse-echo ultrasound to measure the elastic moduli of UTe2 in samples that exhibit both one and two superconducting transitions. We demonstrate the absence of thermodynamic discontinuities in the shear elastic moduli of both single- and double-transition samples, providing direct evidence that UTe2 has a single-component superconducting order parameter. We further show that superconductivity is highly sensitive to compression strain along the a and c axes, but insensitive to strain along the b axis. This leads us to suggest a single-component, odd-parity order parameter—specifically the B2u order parameter—as most compatible with our data.


spin-triplet superconductivity, ultrasound, elastic constants


Theuss, F. , Shragai, A. , Grissonnanche, G. , Hayes, I. , Saha, S. , Eo, Y. , Suarez, A. , Shishidou, T. , Butch, N. , Paglione, J. and Ramshaw, B. (2023), Single-Component Superconductivity in UTe2 at Ambient Pressure, arxiv, [online],, (Accessed April 19, 2024)
Created July 21, 2023, Updated March 13, 2024