NMR study of spin fluctuations driving spin-triplet superconductivity in uranium-based heavy fermion materials

ウラン系重い電子系化合物のスピン三重項超伝導をもたらすスピン揺らぎのNMR研究

徳永 陽  

Tokunaga, Yo

Uranium-based heavy fermion materials UGe, URhGe, and UCoGe are the only fully established examples of ferromagnetic (FM) superconductors, in which uniform superconductivity (SC) exists deep inside the FM state. A characteristic feature of these FM superconductors is that they exhibit very large upper critical fields, , by far exceeding the ordinary Pauli paramagnetic limit, providing a strong indication of equal-spin (triplet) SC pairing. Spin fluctuations identified by high-field NMR studies near a FM quantum critical point are suggested to create the binding force between equal-spin pairs. In this talk, the results of our recent NMR studies on a novel spin-triplet superconductor UTe, which exhibits a very large and anisotropic similar to the above-mentioned FM superconductors, will also be presented and discussed.