GdBa_2Cu_3O_(7-δ)单晶的各向异性研究

STUDIES ON ANISOTROPY FOR SINGLE-CRYSTAL GdBa_2Cu_3O_(7-8)

本文报道了对GdBa_2Cu_3O_(7-8)单晶正常态电阻率、超导临界温变,以及磁转变的各向异性观测结果,发现ab平面上及c轴方向的电阻率,除T_c附近由于超导涨落引起的明显偏离以外,在正常态都能很好地满足Anderson-Zou关系:ρ=A/T+BT,但两方向的A,B存在显著差异说明其输运电荷是由不同机制产生,它具有显著的二维特征;沿c轴方向的超导电性比沿ab平面的超导电性要弱,T_(ce)比T_(ce∥)低2K;H∥ab平面时的交流屏蔽效应仅是H⊥ab平面时的76％。

We report the experimental results on anisotropy of the normal state resistivity, transition temperature and magnetic transition in single crystal GdBa2Cu3O7-8. We find that both ρ∥and ρ⊥ are fitted very well to the Anderson-Zou relationship ρ = A/T + BT, except near Tc where fluctuation enhanced conductance becomes prominent. The striking difference in A, B of two directions suggests that charge transport proceeds by different mechanisms in the two directions, that the system exhibit remarkable two-dimensional character in the normal stete. The superconductivity in the c direction is weaker than that in ab plane: Tce⊥is 2K lower than Tce∥. a. c. magnetic shielding effect when H∥ab plane is only 76% of that as H⊥ab plane.