arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2109.02864cond-mat.supr-concond-mat.mtrl-sci
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NaC6:一种潜在的高温超导体的力学、电子学、光学和超导态性质的第一性原理预测

First-principles prediction of pressure dependent mechanical, electronic, optical, and superconducting state properties of NaC6: A potential high-Tc superconductor

Nazmun Sadat Khan, B. Rahman Rano, Ishtiaque M. Syed, R. S. Islam, S. H. Naqib

摘要:

最近,具有方钠石状结构的富碳NaC6已经被预测在相对低的应用(与高Tc的超临界流体静压相比)流体静压下显示出高于100 K的超导转变温度。我们研究了NaC6的结构、弹性、电子、超导态和光电性质与压力的关系。一些重要的热物理性质也进行了探讨。第一次研究了其弹性性质与泊松比、皮尤比和光电参数的关系。发现NaC6仅在40 GPa及以上的高压下结构稳定,与先前的研究一致。该化合物具有高度延展性,化学键合本质上主要是金属。德拜温度表现出很强的压力依赖性。Gruneisen参数也表现出显着的压力依赖性。电子能带结构显示出金属特征,并且由穿过费米能级的高度色散和几乎平坦的能带组成。在40~70 GPa范围内,费米能级上的电子态密度和库仑赝势都随压力的增加而逐渐增加。在E(k)曲线中的分散程度弱地依赖于价带和导带中的压力。首次研究的光学参数谱与电子能带结构有很好的对应关系。NaC6在中紫外区吸收和反射电磁辐射非常有效。在不同的压力下,超导转变温度的NaC6已估计和以前报道的值进行了比较。详细讨论了各种参数对Tc的影响。

英文摘要:

Very recently carbon-rich NaC6 with sodalite-like structure has been predicted to show superconducting transition temperature above 100 K at relatively low applied (compared to high-Tc hydrides) hydrostatic pressures. We have investigated the pressure dependent structural, elastic, electronic, superconducting state, and optoelectronic properties of NaC6 in this study. Some important thermophysical properties have also been explored. The elastic properties along with Poisson's and Pugh's ratios and optoelectronic parameters are investigated for the first time. NaC6 was found to be structurally stable only at high pressures at and above 40 GPa, in agreement with previous study. The compound is highly ductile and the chemical bonding is predominantly metallic in nature. The Debye temperature shows strong pressure dependence. The Gruneisen parameter also exhibits significant pressure dependence. The electronic band structure reveals metallic character and consists of highly dispersive and almost flat bands crossing the Fermi level. Both the electronic density of states at the Fermi level and repulsive Coulomb pseudopotential increase gradually with increasing pressure in the range 40 GPa to 70 Gpa. The degree of dispersion in the E(k) curves depend weakly on pressure both in the valence and conduction bands. The optical parameters spectra, studied for the first time, correspond well with the electronic band structure. NaC6 absorbs and reflects electromagnetic radiation quite efficiently in the mid-ultraviolet region. Superconducting transition temperatures of NaC6 have been estimated at different pressures and compared with previously reported values. The effects of various parameters on Tc have been discussed in details.

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