標題: Andreev reflection in two-dimensional relativistic materials with realistic tunneling transparency in normal-metal/superconductor junctions
作者: Chang, Yung-Yeh
Mou, Chung-Yu
Chung, Chung-Hou
電子物理學系
Department of Electrophysics
公開日期: 17-Aug-2017
摘要: The Andreev conductance across realistic two-dimensional (2D) normal-metal (N)/superconductor (SC) junctions with a relativistic Dirac spectrum is theoretically investigated within the Blonder-Tinkham-Klapwijk formalism with tunable tunneling transparency. It is known that due to the effect of Klein tunneling, impurity potentials at the interface of 2D relativistic materials will enhance (not suppress) the tunneling and therefore are not suitable to model a realistic tunnel junction of these materials. Here, we propose a way to construct a more realistic tunnel junction by adding a narrow, homogeneous local strain, which effectively generates a delta-gauge potential and variations of electron hopping at the interface, to adjust the transparency of the N/SC junction. Remarkable suppression of the Andreev conductance is indeed observed in the graphene N/SC junction as the strength of the local strain increases. We also explore the Andreev conductance in a topological N/SC junction at the two inequivalent Dirac points and predict the distinctive behaviors for the conductance across the chiral-to-helical topological phase transition. The relevance of our results for the adatom-doped graphene is discussed.
URI: http://dx.doi.org/10.1103/PhysRevB.96.054514
http://hdl.handle.net/11536/145932
ISSN: 2469-9950
DOI: 10.1103/PhysRevB.96.054514
期刊: PHYSICAL REVIEW B
Volume: 96
Issue: 5
起始頁: 0
結束頁: 0
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