Observation of magnetic order in the heavy-fermion superconductor UBe13

We have measured the magnetostriction L(H) of a single crystal of the heavy-fermion superconductor UBe13 using an all-silicon high-precision capacitance dilatometer. We find clear evidence for a transition to an antiferromagnetic state at TN∼8.8 K, which is suppressed in a field by dTN/dH∼0.36 K/T. At low temperatures we observe pronounced magnetostrictive oscillations, which we believe are de Haas–van Alphen oscillations due to an unusual aspect of the Fermi surface.