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 Tc1.5K 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 0.4K in samples with lower Tc, 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.
All Science Journal Classification (ASJC) codes
- General Physics and Astronomy