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arXiv 2201.00298cond-mat.supr-concond-mat.mtrl-sci
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表面官能团对Nb$_2$C-MXene超导电性的作用:实验与密度泛函理论计算

Role of surface functional groups to superconductivity in Nb$_2$C-MXene: Experiments and density functional theory calculations

Kai Wang, Haolin Jin, Hongye Li, Zhongquan Mao, Lingyun Tang, Dan Huang, Ji-Hai Liao, Jiang Zhang

AI总结:

本研究通过实验与密度泛函理论计算,系统研究了Nb$_2$C-MXene表面官能团对其超导电性的影响,证实Nb$_2$CCl$_x$为转变温度约5.2 K的第二类超导体,而Nb$_2$CF$_x$不超导,澄清了此前矛盾并提供了参考。

摘要:

最近,通过熔盐法制备的Nb$_2$C-MXene中发现的依赖于表面官能团的超导电性引起了广泛关注。然而,关于带有F官能团的Nb$_2$C-MXene(Nb$_2$CF$_x$)的超导电性,实验和理论研究结果存在一些矛盾。在此,我们系统地开展了对带有Cl官能团的Nb$_2$C-MXene(Nb$_2$CCl$_x$)和Nb$_2$CF$_x$的超导电性的实验和理论研究。Meissner效应和零电阻的实验结果证明,Nb$_2$CCl$_x$具有超导电性,其转变温度(Tc)约为5.2 K。我们从电阻率的温度依赖性和磁化强度的场依赖性中提取了其超导参数。Ginzburg-Landau参数K$_G$$_L$估计为2.41,表明Nb$_2$CCl$_x$是典型的第二类超导体。相反,磁性和电输运测量均表明Nb$_2$CF$_x$不具有超导电性。第一性原理密度泛函理论(DFT)计算表明,Nb$_2$CCl$_x$的Tc约为5.2 K,而Nb$_2$CF$_x$在声子谱中具有虚频,动态不稳定,这与实验结果吻合良好。我们的研究不仅有助于澄清目前的不一致性,也为未来MXene超导电性的研究提供了参考意义。

英文摘要:

The recently discovered surface-group-dependent superconductivity in Nb$_2$C-MXene fabricated by the molten salts method is attracting wide attention. However, regarding the superconductivity of Nb$_2$C-MXene with functional F groups (Nb$_2$CF$_x$), there were some conflicting results in experimental and theoretical studies. Herein, we systematically carried out experimental and theoretical investigations on the superconductivity in Nb$_2$C-MXene with the Cl functional group (Nb$_2$CCl$_x$) and Nb$_2$CF$_x$. The experimental results of the Meissner effect and zero resistivity have proved that Nb$_2$CClx is superconducting with the transition temperature (Tc) ~ 5.2 K. We extract its superconducting parameters from the temperature dependence of resistivity and the field dependence of the magnetization. The Ginzburg-Landau parameter K$_G$$_L$ is estimated to be 2.41, indicating that Nb$_2$CClx is a typical type-II superconductor. Conversely, both magnetic and electrical transport measurements demonstrate that Nb$_2$CF$_x$ is not superconducting. The first-principles density functional theory (DFT) calculations show that the Tc of Nb$_2$Cl$_x$ is ~ 5.2 K, while Nb$_2$CF$_x$ is dynamically unstable with imaginary frequency in phonon spectrum, which is in good agreement with the experimental results. Our studies not only are useful for clarifying the present inconsistency but also offer referential significance for future investigations on the superconductivity of MXenes.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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