掺杂EuSr_2Ru_(1-x)Nb_xCu_2O_8体系的磁性和超导电性

Ferromagnetism and Superconductivity in Nb-doped EuSr_2Ru_(1-x)Nb_xCu_2O_8 System

通过对EuSr2 Ru1-xNbxCu2 O8体系的结构、磁化强度和电阻进行观测 ,结果发现 :EuSr2 RuCu2 O8样品呈现超导电性和铁磁性共存 .其超导临界温度为Tconset≈ 35K ,Tc(ρ =0 ) =10K ,铁磁相变温度为TM=130 .2K ;Nb部分替代Ru同时导致铁磁相变温度和超导临界温度的下降 ,前者进一步说明了EuSr2 RuCu2 O8体系中磁有序仅来源于Ru的磁矩 ,而超导临界温度的下降则是由于CuO2 平面载流子浓度下降所致 .

The structural,magnetic and transport properties have been investigated for EuSr 2Ru 1-xNb xCu 2O 8 system.It is found that EuSr 2RuCu 2O 8 compound exhibits coexistence of ferromagnetism and superconductivity with superconducting critical temperature T c onset=35 K,T c(ρ=0)=10 K and ferromagnetic transition temperature T M=130.2 K.The experimental results show that partial substitution of Nb for Ru in this system results in the decrease of the ferromagnetic transition temperature T M and superconducting critical temperature.The former further supports the idea that the ferromagnetic order involves only Ru moments in EuSr 2RuCu 2O 8 compound,however,the decrease of superconducting critical temperature T c originates from the decrease of carrier concentration in CuO 2 plane.