Avoided antiferromagnetic order and quantum critical point in CeCoIn₅

We measured the specific heat and resistivity of heavy fermion CeCoIn₅ between the superconducting critical field _c2 = 5 T and 9 T, with the field in the [001] direction, and at temperatures down to 50 mK. At 5 T the data show a non-Fermi liquid (NFL) behavior down to the lowest temperatures. At the field above 8 T the data exhibit a crossover from the Fermi liquid to a non-Fermi liquid behavior. We analyzed the scaling properties of the specific heat and compared both the resistivity and the specific heat with the predictions of a spin-fluctuation theory. Our analysis leads us to suggest that the NFL behavior is due to incipient antiferromagnetism (AFM) in CeCoIn₅ with the quantum critical point in the vicinity of H_c2. Below H_c2 the AFM phase which competes with the paramagnetic ground state is superseded by the superconducting transition.