Hall effect measurements have been conducted on high-quality single crystals of the heavy-fermion superconductor CeCoIn5. The anomalous Hall contribution is negligible in the investigated temperature range from 0.05 to 5 K. The measured Hall resistivities ρxy show a noticeable change in slope between the low-field (initial Hall coefficient) and the high-field region. In the superconducting regime, T < 2.3 K, Hall measurements are restricted to high magnetic fields H > Hc 2, the upper critical field of superconductivity. The high-field Hall coefficient is almost constant for temperatures down to 250 mK. At T {less-than or slanted equal to} 250 mK, an additional change in curvature of ρxy vs. H is observed. © 2006 Elsevier B.V. All rights reserved.

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.