量子线/铁基超导隧道结中隧道谱的研究

Tunneling spectra for quantum wire/iron-based superconductor junction

考虑铁基超导中能带间的相互作用和界面对每一个能带的散射作用,利用推广的Blonder-TinkhamKlapwijk模型,并通过求解Bogoliubov-de Gennes方程研究了具有不同类型双能隙系统的量子线/铁基超导隧道结中准粒子的输运系数和隧道谱.研究表明:1)在弹道极限时,随着带间相互作用的增大,s±波隧道谱中零偏压附近的平台演变成电导峰;s++波的平台演变成凹陷;p波的零偏压电导峰被压低.2)界面对两个能带的散射作用不为零时,随着带间相互作用的增大,s±波和s++波两能隙处的峰值将降低,而两峰间的凹陷值将变大;p波的零偏压电导峰被压低,非零偏压电导增大.3)界面对每个能带的散射,可使其产生的电导峰变得更加尖锐,但可压低和抹平另一个带产生的电导峰值.这些结果对于澄清铁基超导体的能隙结构和区别不同类型铁基超导体有所帮助.

Taking into account the interface scattering effect on each band （in-band interaction） and the interaction between the bands （inter-band interaction）, within an extended Blonder-Tinkham-Klapwijk scattering formalism, we have studied the quasi-particle transport coe？cients and the tunneling spectrum for quantum wire/iron-based superconductor junction of different types of two-level system by solving the Bogoliubov-de Gennes equations. It has been shown that： 1） When the junction is in ballistic limit, the platform near zero bias of the s±-wave tunneling spectroscopy will become a conductance peak as the inter-band interaction increases, while a dip occurs in s＋＋-wave tunneling spectroscopy, and the zero-bias conductance peak will be depressed for p-wave. 2） When the interface scattering effect is not zero, the peaks in the two energy gaps of both s±-wave and s＋＋-wave iron-based superconductor will be depressed; as the inter-band interaction increases, the dip between the two peaks will increase, moreover, the value of zero-bias conductance peaks for p-wave will be lowered and the value of nonzero-bias conductance will be increased. 3） As the in-band interaction is increased, the self-conductance peak will become sharper, while the another conductance peak is not only lowered but also smoothed. These results will be helpful for clarifying the structure of the pair-potential in iron-based superconductor and distinguishing their types.