Identification of Non-unitary triplet pairing in a heavy Fermion superconductor UPt_3

Abstract

A NMR experiment recently done by Tou et al. on a heavy Fermion superconductor UPt${}_3$ is interpreted in terms of a non-unitary spin-triplet pairing state which we have been advocating. The proposed state successfully explains various aspects of the seemingly complicated Knight shift behaviors probed for major orientations, including a remarkable d-vector rotation under weak fields. This entitles UPt${}_3$ as the first example that a charged many body system forms a spin-triplet odd-par ity pairing at low temperatures and demonstrates unambiguously that the putative spin-orbit coupling in UPt${}_3$ is weak.

4 pages, 2 eps figures, to be published in J. Phys. Soc. Jpn. 67 (1998) No.4