正常金属/超导/正常金属双垒隧道结中的量子相干输运

考虑到量子相干效应和界面散射效应 ,利用 L ambert理论模型 ,计算正常金属 /绝缘层 /超导 /绝缘层 /正常金属双垒隧道结中的准粒子输运系数和隧道谱。研究表明 :( 1)所有的准粒子输运系数和电导谱在超导能隙之上都随能量作周期性振荡 ,其振荡周期依赖于超导层的厚度 ;( 2 )在超导能隙之上 Andreev反射系数随能量呈现周期性消失现象 ;( 3)在绝缘层势垒强度取很大的隧道极限下 ,超导层中会形成一系列的准粒子束缚态 ,其位置由量子化条件决定 ;( 4)界面散射效应不仅能压低各子能隙电导峰 ,还能使子能隙电导峰劈裂为两个峰。

Coherent Quantum Transport in Normal Metal/Superconductor/Normal Metal Double Tunnel Junctions

Taking into account the quantum coherent effect and the interfacial scattering effect, applying the Lambert formula, we calculate the quasiparticle transport coefficients and tunneling spectrum in normal metal /insulator/superconductor/insulator/normal metal double tunnel junctions. It is shown that (1) all quasiparticle transport coefficients and conductance spectrum exhibit oscillating behavior with the energies above superconducting gap, the oscillation period depends on the thickness of superconductor interlayer; (2) Andreev reflection exhibits a periodic vanishing with the energies; (3) in the tunnel limit, a series of bound states of quasipaticle are formed, and the position of these bound states are determined by the quantization conditions; (4) the subgap conductance peaks are not only lowed, but also gradually split the two peaks with the increase of the interfacial scattering strength.