Anomalous Andreev reflection in an 8-Pmmn borophene-based superconducting junction

Xingfei Zhou

doi:10.1103/PhysRevB.102.045132

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Anomalous Andreev reflection in an 8-Pmmn borophene-based superconducting junction

Xingfei Zhou

DOI 10.1103/PhysRevB.102.045132 · Physical Review B

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Abstract

We investigate the Andreev reflection in an 8-Pmmn borophene-based normal metal-superconductor junction by solving the Dirac–Bogoliubov–de Gennes equation. There are three unusual features for Andreev reflection of anisotropic massless Dirac fermion: (1) The Andreev retroreflection generates in the interband conversion. (2) The specular Andreev reflection generates in the intraband conversion. (3) The electron-hole conversion with unit efficiency happens at a nonzero incident angle of electron regardless of the magnitude of doping in normal and superconducting regions. These three unique properties are opposite to the ones in a graphene-based normal metal-superconductor junction due to the anisotropic band structure of 8-Pmmn borophene. Interestingly, we can modulate the Andreev reflection by adjusting the direction of junction. Our work gives an insight into the understanding of Andreev reflection of Dirac fermion.