Hall effect and magnetoresistance of YbAl3

We have recently grown high-quality single crystals of YbAl3 with a large residual resistivity ratio (similar to 60). This paper will report on the temperature dependence of the Hall coefficient and the magnetoresistance in the longitudinal and transverse configurations (Bparallel toI and Bperpendicular toI, respectively). The derivative of the Hall coefficient changes sign at around 50 K, below which the magnetic susceptibility starts to increase and the specific-heat coefficient shows a rapid drop. The magnetoresistance data reveal a different field dependence below and above 50 K: at T > 50 K, the magnetoresistance varies with the square of magnetic field but changes to a different power-law behavior at lower temperature. We suggest that in YbAl3 there is a low-temperature scale for the onset of coherence at T* = 50 K. (C) 2002 Elsevier Science B.V. All rights reserved.