Anisotropic magnetoresistance in UBe13

Angular dependence of the transverse magnetoresistance of a heavy-fermion s uperconductor UBe13 (T-c = 0.9 K) was measured on a single crystal grown by the Al-flux method. The resistivity decreases with increasing the magnetic field at low temperatures, indicating that a magnetic scattering is suppre ssed by the magnetic field. We observed a remarkable angular dependence in magnetoresistance at 0.45 K under a constant held of 13 T, showing a minimu m at the [1 1 0] direction. This anisotropy of magnetoresistance is observe d below 4 K. Since the large resistivity (200 mu Ohm cm) of this compound a t low temperatures is attributed to the magnetic scattering by uranium ions , the present anisotropy in the magnetic scattering at low temperatures wou ld give important information about the ground state of 5f electrons. (C) 1 999 Elsevier Science B.V. All rights reserved.