EuSr_2RuCu_(2-x)Zn_xO_8中Zn对Cu的替代效应

EFFECT OF Zn SUBSTITUTION IN EuSr_2RuCu_2O_8

通过对 EuSr2RuCu2-xZnxO8超导体系的结构、电阻和磁化强度的观测,研究了 Zn对Cu的部分替代对其超导电性和磁性的影响.结果表明,Zn部分替代 Cu后 Eusr2RuCu2-ZnxO8体系仍能保持单相的上限浓度为x=0.2;替代导致样品发生四方-正交的结构相变,并对其超导电性具有强烈的破坏作用,x=0.01的样品在4.2K以上已不再呈现超导电性;替代增强了 Ru离子之间的铁磁相互作用,导致铁磁相变温度的提高.

Polycrystalline samples of EuSr2RuCu2-xZnxO8+y (x=0, 0.02 and 0.2) were prepared by a conventional solid-state reaction method. The influences of the partial substitution of Zn for Cu on the superconductivity and magnetic properties of EuSr2RuCu2-xZnxO8 were studied by means of the measurements of the structure, resistance and magnetization. The results show that the upper-limit concentration of the samples consist of single-phase is x=0.2 and the partial substitutions of Zn for Cu result in the tetragonal-to-orthorhombic phase transition. The partial substitution of Zn for Cu destroys the superconductivity. The x=0.01 sample is not superconductive above 4.2 K, because the pure EuSr2RuCu2O8 (x=0) sample is an underdoped high-Tc superconductor, and its Tc is very low. The partial substitutions of Zn for Cu result in the increase of ferromagnetic transition temperature, which indicates that this substitutions increase the ferromagnetic interaction between Ru ions.