Specular andreev Reflection in graphene
Specular andreev Reflection in graphene
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DOI：
10.1103/physrevlett.97.067007
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发表时间：
2006-08-11
影响因子：
8.6
通讯作者：
Beenakker, C. W. J.
中科院分区：
文献类型：
--
作者：
Beenakker, C. W. J.
将相对论量子力学中的Dirac方程与超导的Bogoliubov-de Gennes方程相结合，研究了石墨烯中正常金属-超导体界面上的电子-空穴转换。我们发现狄拉克费米子的Andreev反射有几个不同寻常的特征：(1)电子和空穴占据不同的能带结构谷；(2)在法向入射下，尽管界面两侧的费米波长存在较大的不匹配，但电子-空穴转换仍以单位效率发生；而且，最根本的是：(3)远离法射入角，反射角可能与入射角相同（反向反射），也可能相反（镜面反射）。当费米波长相对于超导相干长度较大时，弱掺杂石墨烯中的Andreev反射占主导地位。
By combining the Dirac equation of relativistic quantum mechanics with the Bogoliubov-de Gennes equation of superconductivity we investigate the electron-hole conversion at a normal-metal-superconductor interface in graphene. We find that the Andreev reflection of Dirac fermions has several unusual features: (1) the electron and hole occupy different valleys of the band structure; (2) at normal incidence the electron-hole conversion happens with unit efficiency in spite of the large mismatch in Fermi wavelengths at the two sides of the interface; and, most fundamentally: (3) away from normal incidence the reflection angle may be the same as the angle of incidence (retroreflection) or it may be inverted (specular reflection). Specular Andreev reflection dominates in weakly doped graphene, when the Fermi wavelength in the normal region is large compared to the superconducting coherence length.