Superconducting state of Sr₂RuO₄ under magnetic fields

The layered perovskite Sr₂RuO₄ exhibits unconventional superconductivity below 1.5 K. There are now several key experimental facts which indicate that its superconducting symmetry is spin-triplet, p-wave, but some important features of its gap structure still need to be determined. In order to address some of the outstanding issues, we have performed a study of its thermodynamic behavior in the field-temperature phase diagram. Specific heat measurements give evidence for multiple superconducting gaps. We will discuss implications of this in relation to the idea of 'orbital-dependent superconductivity'. We will also present the results of a search for a second superconducting transition under the magnetic field applied precisely parallel to the quasi-two-dimensional plane.