Search for antiferromagnetic order inUBe13via magnetovolume effects

The linear magnetostriction (λ) and the coefficient of linear thermal expansion (α) of a single-crystalline sample of the heavy-fermion compound ${\mathrm{UBe}}_{13}$ have been determined for elongation directions along and perpendicular to the applied magnetic field (B∥[100]), in the temperature interval 0.3<T<12 K and for fields B<8 T. We find neither evidence for antiferromagnetic order (${\mathit{T}}_{\mathit{N}}$=8.8 K), nor for magnetostrictive oscillations, which were reported recently by Kleiman et al. [Phys. Rev. Lett. 64, 1975 (1990)]. Instead λ varies proportional to ${\mathit{B}}^2$ as expected for a normal paramagnetic metal. The low-temperature normal-state electronic Grüneisen parameter is unusually large and drops rapidly in the superconducting phase (${\mathit{T}}_{\mathit{c}}$=0.85 K). We also report magnetostriction measurements on ${\mathrm{UBe}}_{13}$ below ${\mathit{T}}_{\mathit{c}}$. The magnetovolume effects in the superconducting phase are strongly anisotropic and reveal a large hysteresis.