Magnetic and fermi surface properties of antiferromagnet EuCd₁₁

We succeeded in growing a high-quality single crystal of EuCd₁₁ with the BaCd₁₁-type tetragonal structure by the Cd self-flux method, and measured the electrical resistivity, specific heat, magnetic susceptibility, magnetization, and de Haas-van Alphen (dHvA) oscillations, together with the electrical resistivity under high pressures up to 8 GPa. The antiferromagnetic ordering was confirmed to occur at the Néel temperature TN = 2.7 K, and the antiferromagnetic state was found to change into the field-induced ferromagnetic state with 7 _{μ; B}/Eu above a critical field H_c ≃ 15 kOe for both the magnetic fields H ∥ [100] and [001], revealing a typical Eu-divalent antiferromagnet. Reflecting the large lattice parameters of a = 11.93Å and c = 7.682Å with the caged structure, where each Eu atom is surrounded by a polyhedron of 22 Cd atoms, the Brillouin zone and the corresponding Fermi surfaces are small in volume. The detected dHvA branches are well explained by the full potential linear augmented plane wave (FLAPW) energy band calculations for the non-4 f reference compound SrCd ₁₁, revealing ellipsoidal Fermi surfaces with complicated concave and convex shapes. The present Eu-divalent electronic state is found to be robust against high pressures up to 8 GPa, and does not change into the Eu-trivalent state.