Hall effect, magnetoresistance, and critical fields of UBe₁₃ thin films

We report the first Hall effect measurements on polycrystalline thin films of the heavy fermion superconductor UBe₁₃. Measurements have been extended to temperatures well below previous studies on single crystals. We find no sign change of the Hall coefficient when cooling through T_c in contrast to the earlier study. We also observe a "shorting" of the Hall voltage below T_c. As the field is swept up, a p-type Hall signal is observed above a threshold magnetic-field which we define as H_c2. The slope of the phase boundary defined by these values agrees well with that as defined by resistivity measurements. Below T = 0.2 K, the magnetoresistance and Hall signal have very little temperature or field dependence above H_c2. The resistivity as a function of field may be fit using a spin- 1 2 Coqblin-Schreiffer model.