K_(0.8)Fe_2Se_2晶体c轴向载流子输运特性的研究  

Investigation of carrier transport properties along the c-axis in K_(0.8)Fe_2Se_2 superconducting crystals

作　　者：晏潜 陆翠敏[1] 冯电稳 杨巍巍[1] 赵捷[1,2] 刘庆锁[1] 马永昌[1,3] 

机构地区：[1]天津理工大学材料科学与工程学院,天津300384 [2]显示材料与光电器件省部共建教育部重点实验室,天津300384 [3]天津市光电显示材料与器件重点实验室,天津300384

出　　处：《物理学报》2014年第3期382-387,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10704054)资助的课题~~

摘　　要：成功制备了超导临界温度为27 K的K0.8Fe2Se2晶体,并详细研究了晶体c轴向的载流子输运特性.结合X射线衍射、光学显微镜下的形貌、变温电阻率的测试结果表明,样品存在有"相分离",但是这类层状铁基超导体材料的两个相不是简单沿c轴向层状交替排布的,而应该是沿着c轴向存在弱联系的金属相链接通路,金属相部分形成近3维的空间网状链接模式.热导率测试和复阻抗谱z(ω,T0)的研究表明超导晶体沿着c轴方向存在有大量的相界面,所束缚的极化电荷致使相对介电常数达到106数量级,相应地在10 MHz附近出现负的相位特征.We have successfully prepared the iron-based superconductor K0.8Fe2Se2 crystals （Tc = 27 K） and studied the carrier transport properties along the c-axis in detail. Samples are characterized by XRD, SEM and temperature-dependent resistivity. The result shows that there is “phase separation” in the samples. Based on the experimental results, the iron-based superconductor is not a simple two phases alternating along the c-axis, but the metal phases should have weak-link channels along the c-axis, forming a nearly 3D special net mode. Studies of the thermal conductivity and the complex impedance spectrum z（omega, To） suggest that the superconducting crystals have a lot of grain boundaries along the c-axis direction, the bound polarization charges result in relative dielectric constant of about 10^6 in magnitude and negative phase characteristics in the vicinity of 10 MHz.

关 键 词：铁基超导体 输运特性 阻抗谱 相分离 

分 类 号：O469[理学—凝聚态物理]