Probing the quantum critical behavior of CeCoIn5 via Hall effect measurements

We present highly sensitive Hall effect measurements of the heavy fermion compound CeCoIn5 down to temperatures of 55 mK. A pronounced dip in the differential Hall coefficient | partial differential rho(xy)/ partial differential H| at low temperature and above the upper critical field of superconductivity, H(c2), is attributed to critical spin fluctuations associated with the departure from Landau Fermi liquid behavior. This identification is strongly supported by a systematic suppression of this feature at elevated pressures. The resulting crossover line in the field-temperature phase diagram favors a field induced quantum critical point at mu(0)H(qc) approximately 4.1 T below H(c2)(T=0) suggesting related, yet separate, critical fields.