%0 Journal Article %T Zero-field Quantum Critical Point in CeCoIn$_5$ %A Y. Tokiwa %A P. Gegenwart %A E. D. Bauer %J Physics %D 2013 %I arXiv %R 10.1103/PhysRevLett.111.107003 %X Quantum criticality in the normal and superconducting state of the heavy-fermion metal CeCoIn$_5$ is studied by measurements of the magnetic Gr\"{u}neisen ratio, $\Gamma_H$, and specific heat in different field orientations and temperatures down to 50 mK. Universal temperature over magnetic field scaling of $\Gamma_H$ in the normal state indicates a hidden quantum critical point at zero field. Within the superconducting state the quasiparticle entropy at constant temperature increases upon reducing the field towards zero, providing additional evidence for zero-field quantum criticality. %U http://arxiv.org/abs/1306.3472v3