Response of Superconductivity and Crystal Structure of LiFeAs to Hydrostatic Pressure
Response of Superconductivity and Crystal Structure of LiFeAs to Hydrostatic Pressure
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DOI：
10.1021/ja808914a
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发表时间：
2009-03-04
影响因子：
15
通讯作者：
Clarke, Simon J.
中科院分区：
文献类型：
--
作者：
Mito, Masaki;Pitcher, Michael J.;Clarke, Simon J.
在高达1.3 Gpa的静水压力作用下，生命样品的超导转变温度(T-c)在大约-2 K Gpa(-1)下近似单调地降低。在金刚石顶压室中用氦气加压介质在静水压下对X射线粉末衍射谱进行了测量，测得其体积寿命为57.3(6)Gpa，远小于其他层状砷化物和含氧砷化物超导体的体积弹性系数。LIFAS还表现出比其他层状砷化铁超导体更大的各向同性压缩。更高和更各向同性的可压缩性可能是锂离子尺寸较小的结果。在常压下，FeAs4四面体在基面上的压缩程度是所有超导砷化铁中最大的。随着压力的增加，Fe-Fe距离比Fe-As距离收缩得更快，从而使FeAs4四面体更加偏离理想的四面体形状。因此，T-c随外加压力的降低与所研究的砷化铁和相关材料中的焦油相一致，当FeAs4四面体接近规则时，对于特定的电子计数，T是最大的。
On the application of hydrostatic pressures of up to 1.3 GPa, the superconducting transition temperatures (T-c) of samples of LiFeAs are lowered approximately monotonically at approximately -2 K GPa(-1). Measurements of the X-ray powder diffraction pattern at hydrostatic pressures of up to 17 GPa applied by a He gas pressure medium in a diamond anvil cell reveal a bulk modulus for LiFeAs of 57.3(6) GPa which is much smaller than that of other layered arsenide and oxyarsenide superconductors. LiFeAs also exhibits much more isotropic compression than other layered iron arsenide superconductors. The higher and more isotropic compressibility is presumably a consequence of the small size of the lithium ion. At ambient pressure the FeAs4 tetrahedra are the most compressed in the basal plane of those in any of the superconducting iron arsenides. On increasing the pressure the Fe-Fe distance contracts more rapidly than the Fe-As distance so that the FeAs4 tetrahedra become even more distorted from the ideal tetrahedral shape. The decrease in T-c with applied pressure is therefore consistent with the observations that in the iron arsenides and related materials investigated thus tar, T. is maximized for a particular electron count when the FeAs4 tetrahedra are close to regular.