美国宾夕法尼亚州立大学Ying Liu团队研究了UTe2中奇奇偶超导电性的观测。该研究于2025年3月25日发表在《美国科学院院刊》上。
序参数的对称性是超导体最基本的特征之一。UTe2被发现具有非常大的上临界场和在低温下引人注目的折返行为，人们普遍认为它具有自旋-三重态配对对称性。然而，仍然缺乏这种配对对称性的明确证据，特别是在零磁场和低磁场下。UTe2中反转晶体对称性的存在要求，如果它确实是自旋三重态超导体，序参数必须是奇数奇偶性的。
研究组报告了使用约瑟夫森效应对序参量轨道部分对称性的相敏测量。s波超导体In和UTe2之间约瑟夫森耦合的取向依赖性的选择规则强烈表明，UTe2在零磁场附近具有B1u对称的奇奇偶配对状态，使其成为自旋三重态超导体。此外还报道了UTe2（110）表面上Andreev表面束缚态的明显形成。
附：英文原文
Title: Observation of odd-parity superconductivity in UTe2
Author: Li, Zixuan, Moir, Camilla M., McKee, Nathan J., Lee-Wong, Eric, Baumbach, Ryan E., Maple, M. Brian, Liu, Ying
Issue&Volume: 2025-3-25
Abstract: Symmetry properties of the order parameter are among the most fundamental characteristics of a superconductor. UTe2, which was found to feature an exceedingly large upper critical field and striking reentrant behavior at low temperatures, is widely believed to possess a spin-triplet pairing symmetry. However, unambiguous evidence for such a pairing symmetry is still lacking, especially at zero and low magnetic fields. The presence of an inversion crystalline symmetry in UTe2 requires that, if it is indeed a spin-triplet superconductor, the order parameter must be of odd parity. We report here phase-sensitive measurements of the symmetry of the orbital part of the order parameter using the Josephson effect. The selection rule in the orientation dependence of the Josephson coupling between In, an s-wave superconductor, and UTe2 suggests strongly that UTe2 possesses the odd-parity pairing state of B1u symmetry near zero magnetic field, making it a spin-triplet superconductor. We also report the apparent formation of Andreev surface bound states on the (110) surface of UTe2.
DOI: 10.1073/pnas.2419734122
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2419734122