title: Anisotropic superconducting gap in the spin-triplet superconductor Sr2RuO4: evidence from a Ru-NQR study
abstract: We have investigated a gap structure in the spin-triplet superconductor Sr2RuO4 through the measurement of the 101Ru nuclear spin-lattice relaxation rate (101)(1/T1) down to 0.09 K at zero magnetic field. In the superconducting state, 1/T1 in a high-quality sample with T(c) approximately 1.5 K exhibits a sharp decrease without the coherence peak, followed by a T3 behavior down to 0.15 K. This result is in marked contrast to the behavior observed below approximately 0.4 K in samples with lower T(c), where T1T is a constant. This behavior is demonstrated to be not intrinsic. We conclude that the gap structure in Sr2RuO4 is significantly anisotropic, consistent with line-node-like models.
authors.affiliation: Department of Physical Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
authors.initials: K
authors.lastname: Ishida
authors.initials: H
authors.lastname: Mukuda
authors.initials: Y
authors.lastname: Kitaoka
authors.initials: ZQ
authors.lastname: Mao
authors.initials: Y
authors.lastname: Mori
authors.initials: Y
authors.lastname: Maeno