Interplay of superconductivity and structural phase transition in the clathrate Ba6Ge25
Interplay of superconductivity and structural phase transition in the clathrate Ba6Ge25
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包合物 Ba6Ge25 中超导性和结构相变的相互作用
DOI：
10.1103/physrevb.70.174512
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发表时间：
2004
影响因子：
3.7
通讯作者：
F. Steglich
中科院分区：
文献类型：
--
作者：
Huiqiu Yuan;F. Grosche;W. Carrillo‐Cabrera;V. Pacheco;G. Sparn;M. Baenitz;U. Schwarz;Y. Grin;F. Steglich
立方化合物在 200 K 左右经历结构相变，低于该温度电阻率突然增加。然而，在这种“不良”金属状态下，类似 BCS 的超导性会在非常低的温度下发生。通过施加静水压力，结构相变被抑制在30℃，但超导转变温度显着升高，达到最高ofat。为了理解这些不寻常的性质，我们测量了压力下的上临界磁场及其同构化合物，从中确定了费米能量下的态密度。它表明，结构相变导致 显着降低（约 4 倍），因此大大削弱了超导性。此外，发现压力下的急剧增强仅受 控制。
The cubic compoundundergoes a structural phase transition around 200 K, below which the electrical resistivity increases abruptly. However, out of this “bad” metallic state, BCS-like superconductivity occurs at very low temperature. By applying hydrostatic pressure, the structural phase transition is suppressed at, but the superconducting transition temperatureincreases remarkably, reaching a maximum ofat. To understand these unusual properties, we have measured the upper critical magnetic fieldforand its isostructural compoundunder pressure, from which the density of states at the Fermi energyis determined. It demonstrates that, in, the structural phase transition causes a significant reduction of(by a factor of about 4) and therefore largely weakens superconductivity. Furthermore, the drastic enhancement ofunder pressure is found to be solely governed by.