论文标题
费米 - 液体非绝热的高度压缩碘化铯超导体
Fermi-liquid nonadiabatic highly-compressed cesium iodide superconductor
论文作者
论文摘要
压缩硫氢的实验发现表现出超导过渡温度TC = 203 K（Drozdov等人2015年自然525 73）引发了对超导氢化物的深入研究。 However, this discovery was not a straight forward experimental examination of theoretically predicted phase, instead it was nearly five-decade long experimental quest for superconductivity in highly-compressed matters, which varied from pure elements (hydrogen, oxygen, sulphur, lithium), cuprates, and hydrides (SiH4, YH3, and AlH3), to semiconductors and ionic salts.其中一种盐是碘化铯CSI，该盐在p = 115 gpa时转化为金属状态，在p = 180 GPa时，该化合物表现出超导转变温度TC〜2 K的发作（Eremets等人，1998年，1998年科学281 1333）。详细的第一原理计算（Xu et al 2009 Phys Rev B 79 144110）表明，在Eliashberg超导性理论中，CSI应在压力P = 180 GPA时表现出TC = 0.03 K，这是由比观察到的值低的两个学位。为了理解这种差异的性质，我们在这里分析了压缩CSI中温度依赖性抗性，发现该化合物是Debye温度TD与Fermi Energy的完美Fermi液体金属，其比例极高（〜17）。这意味着对这种化合物的直接利用对于这种化合物是不正确的，因为该理论适用于TD/TF << 1。我们还表明，高度压缩的CSI表现出TC/TF = 0.04-0.07的比率，并且在Uemura图中它在非常规上负责的频带中属于TC/TF = 0.04-0.07。
Experimental discovery that compressed sulphur hydride exhibits superconducting transition temperature Tc=203 K (Drozdov et al 2015 Nature 525 73) sparked intensive studies of superconducting hydrides. However, this discovery was not a straight forward experimental examination of theoretically predicted phase, instead it was nearly five-decade long experimental quest for superconductivity in highly-compressed matters, which varied from pure elements (hydrogen, oxygen, sulphur, lithium), cuprates, and hydrides (SiH4, YH3, and AlH3), to semiconductors and ionic salts. One of these salts was cesium iodide, CsI, which converts into metallic state at P=115 GPa and at P=180 GPa this compound exhibits the onset of the superconducting transition temperature Tc~2 K (Eremets et al 1998 Science 281 1333). Detailed first principles calculations (Xu et al 2009 Phys Rev B 79 144110) showed that within Eliashberg theory of superconductivity, the CsI should exhibits Tc=0.03 K at pressure P=180 GPa, which is by two orders of magnitude lower than the observed value. In attempt to understand the nature of this discrepancy, here we analyzed temperature dependent resistance in compressed CsI and found that this compound is perfect Fermi liquid metal which exhibits extremely high (~ 17) ratio of the Debye temperature, Td, to the Fermi energy, Tf. This implies that direct utilization of the Eliashberg theory is incorrect for this compound, because the theory valid for the ratio Td/Tf << 1. We also showed that highly-compressed CsI exhibits the ratio of Tc/Tf = 0.04-0.07 and it falls in unconventional superconductors band in the Uemura plot.
