Crystallographic phase transition and high-Tc superconductivity in LaFeAsO:F
Crystallographic phase transition and high-Tc superconductivity in LaFeAsO:F
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DOI：
10.1088/0953-2048/21/12/125028
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发表时间：
2008-12-01
影响因子：
3.6
通讯作者：
Hosono, H.
中科院分区：
文献类型：
--
作者：
Nomura, T.;Kim, S. W.;Hosono, H.
未掺杂的LaFeAsO是新发现的高温超导体的母体化合物，其电阻率随温度的变化在160 K附近急剧下降。F掺杂可以抑制这种反常现象，同时出现相应的超导电性，表明这种反常现象与超导电性密切相关。我们研究了未掺杂（正常导体）和14 at.%通过同步X射线衍射（XRD）、直流磁测量和从头计算等方法对掺F LaFeAsO（Tc = 20 K）样品进行了研究，结果表明：在160 K附近，样品发生了从四方相（P4/nmm）到正交相（Cmma）的相变，在140 K附近，样品发生了反铁磁自旋有序转变.这些转变可以解释自旋构型依赖的势能面从从头计算。的过渡的抑制归因于相互关联的影响的几何和电子结构的变化，由于掺杂的F-离子。S补充数据可从stacks.iop.org/SUST/21/125028获得
Undoped LaFeAsO, the parent compound of the newly found high-T-c superconductor, exhibits a sharp decrease in the temperature-dependent resistivity at similar to 160 K. The anomaly can be suppressed by F doping with simultaneous appearance of superconductivity appears correspondingly, suggesting a close association of the anomaly with the superconductivity. We examined the crystal structures, magnetic properties and conductivity of undoped (normal conductor) and 14 at.% F-doped LaFeAsO (T-c = 20 K) by synchrotron x-ray diffraction (XRD), DC magnetic measurements, and ab initio calculations demonstrated that the anomaly is associated with a phase transition from tetragonal (P4/nmm) to orthorhombic (Cmma) phases at similar to 160 K as well as an antiferromagnetic spin ordering transition at similar to 140 K. These transitions can be explained by spin configuration-dependent potential energy surfaces derived from the ab initio calculations. The suppression of the transitions is ascribed to interrelated effects of geometric and electronic structural changes due to doping by F-ions. S Supplementary data are available from stacks.iop.org/SUST/21/125028