物理学院 School of Physics, Nanjing University

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Half-quantized conductance plateaus in topological insulator-superconductor heterostructures

2017年12月16日

   时间:12月18日上午10:45
  地点:唐楼A213
  报告人:
新加坡国立大学  Jiangbin Gong教授

Abstract: The past few years have witnessed increased attention to the quest for Majorana-like excitations in the condensed matter community.  As a promising candidate in this race, the one-dimensional chiral Majorana edge mode (CMEM) in  topological insulator-superconductor heterostructures has gathered renewed interests during recent months after an experimental breakthrough.  We study the quantum transport of topological insulator-superconductor hybrid devices subject to light-matter interaction  or general time-periodic modulation. We report quantized conductance plateaus at one-half and three-half of  the conductance quantum (electron charge squared over the Planck constant),  upon applying the so-called Floquet sum rule.  In particular, in a photoinduced topological superconductor sandwiched between two Floquet Chern insulators, it is found that for each Floquet sideband, the CMEM admits equal probability for normal transmission and local Andreev reflection over a wide range of parameter regimes, yielding half-integer quantized plateaus that resist static and time-periodic disorder.  The three-half plateau has not yet been computationally or experimentally observed in any other superconducting system and indicates the possibility to simultaneously create and manipulate multiple pairs of CMEMs by light. The robust half-quantized conductance plateaus are both fascinating and subtle because they only emerge after a summation over contributions from all Floquet sidebands.  Such a distinctive transport signature can thus serve as a hallmark of photoinduced CMEMs in topological insulator-superconductor junctions.  

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