Thermal conductivity of superconducting Sr2RuO4 in oriented magnetic fields - art. no. 064505

We report in-plane thermal conductivity along [100] direction, kappa (100), of high quality single crystals (T-c = 1.44 K) of unconventional supercond uctor Sr2RuO4. Measurements were performed as a function of temperature T a nd magnetic fields H of various orientations. Linear decrease of kappa (100 )/T in T in zero field is found below 1 K, in contrast to nearly constant v alue in the normal state. Field dependence of kappa (100)/T at 0.3 K in H p erpendicular to the plane is qualitatively similar to that for a line-node superconducting state in the low temperature limit. The dependence gives mu H-0(c1) approximate to 8 mT and mu H-0(c2) approximate to 60 mT. In the in -plane fields, the field dependence at low temperatures shows a notable dif ference from the perpendicular field case. The temperature and field domain of this anomalous behavior is consistent with the existence of another sup erconducting phase, as proposed recently.