Resonance from antiferromagnetic spin fluctuations for superconductivity in UTe2
Resonance from antiferromagnetic spin fluctuations for superconductivity in UTe2
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DOI：
10.1038/s41586-021-04151-5
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发表时间：
2021-12-23
期刊：
影响因子：
64.8
通讯作者：
Dai, Pengcheng
中科院分区：
文献类型：
--
作者：
Duan, Chunruo;Baumbach, R. E.;Dai, Pengcheng
超导性源于束缚（库珀）电子对的形成，这些电子可以在低于超导转变温度 T-c 时无阻力地穿过晶格（参考文献（1））。大多数超导体中的电子库珀对形成总自旋 S = 0 的反平行自旋单重态（参考文献（2）），尽管它们也可以形成 S = 1 的平行自旋三重态库珀对和奇宇称波函数（3）。自旋三重态配对很重要，因为它可以承载与量子计算相关的拓扑态和马约拉纳费米子(4,5)。由于自旋三重态配对通常由铁磁 (FM) 自旋涨落介导 (3)，因此接近 FM 不稳定性的铀基材料被认为是实现自旋三重态超导性的理想候选材料 (6)。事实上，UTe2 的 T-c 接近 1.6 K（参考文献（7,8）），已被确定为接近 FM 不稳定性的手性自旋三重态拓扑超导体的候选者 (7-14)，尽管它也具有反铁磁 (AF) 自旋涨落 (15,16)。在这里，我们使用非弹性中子散射 (INS) 来表明 UTe2 中的超导性与 AF 级附近的布里渊区边界处的尖锐磁激励耦合，称为共振 (17-23)。由于共振仅在 AF 不稳定性附近的自旋单线态非常规超导体中发现 (17-23)，因此在 UTe2 中的观察表明 AF 自旋涨落也可能引起自旋三线态配对 (24) 或者 UTe2 中的电子配对具有自旋单线态成分。
Superconductivity originates from the formation of bound (Cooper) pairs of electrons that can move through the lattice without resistance below the superconducting transition temperature T-c (ref. (1)). Electron Cooper pairs in most superconductors form anti-parallel spin singlets with total spin S = 0 (ref. (2)), although they can also form parallel spin-triplet Cooper pairs with S = 1 and an odd parity wavefunction(3). Spin-triplet pairing is important because it can host topological states and Majorana fermions relevant for quantum computation(4,5). Because spin-triplet pairing is usually mediated by ferromagnetic (FM) spin fluctuations(3), uranium-based materials near an FM instability are considered to be ideal candidates for realizing spin-triplet superconductivity(6). Indeed, UTe2, which has a T-c approximate to 1.6 K (refs.(7,8)), has been identified as a candidate for a chiral spin-triplet topological superconductor near an FM instability(7-14), although it also has antiferromagnetic (AF) spin fluctuations(15,16). Here we use inelastic neutron scattering (INS) to show that superconductivity in UTe2 is coupled to a sharp magnetic excitation, termed resonance(17-23), at the Brillouin zone boundary near AF order. Because the resonance has only been found in spin-singlet unconventional superconductors near an AF instability(17-23), its observation in UTe2 suggests that AF spin fluctuations may also induce spin-triplet pairing(24) or that electron pairing in UTe2 has a spin-singlet component.