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arXiv 1604.08686cond-mat.supr-con
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Sr0.5La 0.5FBiSe 2超导体的超导电性和反常压力效应

Superconductivity and abnormal pressure effect in Sr0.5La0.5FBiSe2 superconductor

Lin Li, Yongliang Xiang, Yihong Chen, Wenhe Jiao, Chuhang Zhang, Li Zhang, Jianhui Dai, Yuke Li

摘要:

采用固相反应法合成了一种新的BiSe_2基超导体Sr_(0:5)La_(0:5)FBiSe_2,其超导转变温度为Tc?3.8 K.磁化率低于Tc的强抗磁信号?(T)观察表明超导体的本体性质。与大多数基于BiS2的化合物不同,其中超导性从类似超导的正常状态发展,本发明的化合物表现出低至Tc的金属行为。然而,在弱磁场或压力下,在电阻率达到局部最小值的Tmin附近发生从金属行为到绝缘行为的显著交叉。随着压力的增加,Tc单调下降和Tmin向高温移动,而在低温下的正常状态电阻率的绝对值首先减小,然后随着压力增加到2.5 GPa。这些结果意味着Sr_(0:5)La_(0:5)FBiSe_2的电子结构可能与其他BiS_2基体系中的电子结构不同。

英文摘要:

Through the solid state reaction method, we synthesized a new BiSe2-based superconductor Sr0:5La0:5FBiSe2 with superconducting transition temperature Tc?3.8 K. A strong diamagnetic signal below Tc in susceptibility ?(T) is observed indicating the bulk nature of superconductivity. Different to most BiS2-based compounds where superconductivity develops from a semiconducting-like normal state, the present compound exhibits a metallic behavior down to Tc. Under weak magnetic field or pressure, however, a remarkable crossover from metallic to insulating behaviors takes place around Tmin where the resistivity picks up a local minimum. With increasing pressure, Tc decreases monotonously and Tmin shifts to high temperatures, while the absolute value of the normal state resistivity at low temperatures first decreases and then increases with pressure up to 2.5 GPa. These results imply that the electronic structure of Sr0:5La0:5FBiSe2 may be different to those in the other BiS2-based systems.

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