CeCoIn5 - a quantum critical superfluid

We have made the first complete measurements of the London penetration depth λ ( T ) of CeCoIn 5 , a quantum-critical metal where superconductivity arises from a non-Fermi-liquid normal state. Using a novel tunnel diode oscillator designed to avoid spurious contributions to λ ( T ), we have es-tablished the existence of intrinsic and anomalous power-law behaviour at low temperature. A systematic analysis raises the possibility that the unusual observations are due to an extension of quantum criticality into the superconducting state.