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Retro reflection of electrons at the interface of bilayer graphene and superconductor

Journal Article


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Abstract


  • Electron reflection at an interface is a fundamental quantum transport phenomenon. The most famous electron reflection is the electron→hole Andreev reflection (AR) at a metal/superconductor interface. While AR can be either specular or retro-type, electron→electron reflection is limited to only the specular type. Here we show that electrons can undergo retro-reflection in bilayer graphene (BLG). The underlying mechanism for this previously unknown process is the anisotropic constant energy band contour of BLG. The electron group velocity is fully reversed upon reflection, causing electrons to be retro-reflected. Utilizing a BLG/superconductor junction (BLG/S) as a model structure, we show that the unique low energy quasiparticle nature of BLG results in two striking features: (1) AR is completely absent, making BLG/S 100% electron reflective; (2) electrons are valley-selectively focused upon retro-reflection. Our results suggest that BLG/S is a valley-selective Veselago electron focusing mirror which can be useful in valleytronic applications.

Authors


  •   Ang, Yee Sin S. (external author)
  •   Ma, Zhongshui (external author)
  •   Chao Zhang

Publication Date


  • 2012

Citation


  • Ang, Y. Sin., Ma, Z. & Zhang, C. (2012). Retro reflection of electrons at the interface of bilayer graphene and superconductor. Scientific Reports, 2 (1013), 1-6.

Scopus Eid


  • 2-s2.0-84871856003

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=8202&context=engpapers

Ro Metadata Url


  • http://ro.uow.edu.au/engpapers/5270

Number Of Pages


  • 5

Start Page


  • 1

End Page


  • 6

Volume


  • 2

Issue


  • 1013

Abstract


  • Electron reflection at an interface is a fundamental quantum transport phenomenon. The most famous electron reflection is the electron→hole Andreev reflection (AR) at a metal/superconductor interface. While AR can be either specular or retro-type, electron→electron reflection is limited to only the specular type. Here we show that electrons can undergo retro-reflection in bilayer graphene (BLG). The underlying mechanism for this previously unknown process is the anisotropic constant energy band contour of BLG. The electron group velocity is fully reversed upon reflection, causing electrons to be retro-reflected. Utilizing a BLG/superconductor junction (BLG/S) as a model structure, we show that the unique low energy quasiparticle nature of BLG results in two striking features: (1) AR is completely absent, making BLG/S 100% electron reflective; (2) electrons are valley-selectively focused upon retro-reflection. Our results suggest that BLG/S is a valley-selective Veselago electron focusing mirror which can be useful in valleytronic applications.

Authors


  •   Ang, Yee Sin S. (external author)
  •   Ma, Zhongshui (external author)
  •   Chao Zhang

Publication Date


  • 2012

Citation


  • Ang, Y. Sin., Ma, Z. & Zhang, C. (2012). Retro reflection of electrons at the interface of bilayer graphene and superconductor. Scientific Reports, 2 (1013), 1-6.

Scopus Eid


  • 2-s2.0-84871856003

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=8202&context=engpapers

Ro Metadata Url


  • http://ro.uow.edu.au/engpapers/5270

Number Of Pages


  • 5

Start Page


  • 1

End Page


  • 6

Volume


  • 2

Issue


  • 1013