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 ∼ 8.8K, which is suppressed in a field by dTN/dH ∼ 0.36K/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.