Nishiyama M, Inada Y, Zheng Guo-qing
Department of Physics, Okayama University, Okayama 700-8530, Japan.
Phys Rev Lett. 2007 Jan 26;98(4):047002. doi: 10.1103/PhysRevLett.98.047002. Epub 2007 Jan 23.
We report (11)B and (195)Pt NMR measurements in noncentrosymmetric superconductor Li(2)Pt(3)B. We find that the spin susceptibility measured by the Knight shift remains unchanged across the superconducting transition temperature T(c). With decreasing temperature (T) below T(c), the spin-lattice relaxation rate 1/T(1) decreases with no coherence peak and is in proportion to T3. These results indicate that the Cooper pair is in the spin-triplet state and that there exist line nodes in the superconducting gap function. They are in sharp contrast to those in the isostructural Li(2)Pd(3)B which is a spin-singlet, s-wave superconductor, and are ascribed to the enhanced spin-orbit coupling due to the lack of spatial inversion symmetry. Our finding points to a new paradigm where exotic superconductivity arises in the absence of electron-electron correlations.
我们报告了在非中心对称超导体Li₂Pt₃B中进行的¹¹B和¹⁹⁵Pt核磁共振测量。我们发现，通过奈特位移测量的自旋磁化率在超导转变温度Tc处保持不变。随着温度T降至Tc以下，自旋-晶格弛豫率1/T₁下降且无相干峰，并且与T³成正比。这些结果表明库珀对处于自旋三重态，并且在超导能隙函数中存在线节点。它们与同结构的自旋单重态s波超导体Li₂Pd₃B形成鲜明对比，这归因于由于缺乏空间反演对称性而增强的自旋-轨道耦合。我们的发现指向了一个新的范式，即在没有电子-电子相互作用的情况下出现奇异超导性。
