Magnetization and anisotropy of a HgBa2Ca2Ca2Cu3O8+δ single crystal

Abstract From torque measurements as a function of the angle and the magnetic field, we extract the magnetization curves and the anisotropy factor for a HgBa 2 Ca 2 Cu 3 O 8+δ single crystal. The anisotropy is found γ = 52 ± 3; it is similar to the one found for the HgBa 2 Ca 3 Cu 4 O 10+δ compound by Zech et al. The analysis of the magnetization close to H c2 ( T ) within the fluctuations theory yields the critical fluctuations parameter τ f = (3.9 ± 0.4) 10 −2 and the in-plane penetration depth λ(0) = 1500 ± 100 A . The superconducting planes separation is found of the order of the unit cell length. The upper critical field is estimaated ( d H c 2 d T ) T c 0 ≈ 14 kOe K −1 .