Abstract
We measured the specific heat and resistivity of heavy fermion CeCoIn 5 between the superconducting critical field H c 2 = 4.95 and 9 T, with the field in the [0 0 1] direction, and at temperatures down to 50 mK. These results show that this compound has a quantum critical point (QCP) with the magnetic field as the tuning parameter. For a field of 5 T just above H c 2 the temperature dependence of both specific heat C p ( T ) and resistivity ρ ( T ) show non-Fermi liquid (NFL) behavior down to the lowest temperatures with C p ( T ) ∝ - log ( T ) and ρ ( T ) - ρ ( T = 0 ) ∝ T . For fields above 8 T the data exhibit a crossover from a NFL to a Fermi liquid behavior. Specific heat and resistivity data show behavior predicted by spin-fluctuation theory, suggesting that the NFL behavior is due to incipient antiferromagnetism (AFM) in CeCoIn 5 with the quantum critical point in the vicinity of H c 2 . For fields below H c 2 the AFM phase separated by a QCP from the paramagnetic ground state is not observed, as the system becomes first superconducting.
Published Version
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