2013/01/06 by Haibing Peng, Debtanu De, Bing Lv +2 · 1 citation
Physics and Astronomy · #cond-mat.supr-con #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.88.024515
published as Phys. Rev. B 88, 024515 (2013) · 18 pages, 5 figures, plus Supplementary Material (5 pages, 4 figures)
arxiv created 2013/01/06 · arxiv updated 2013/07/29
CuxBi2Se3 has been proposed as a potential topological superconductor characterized by an odd-parity full bulk superconducting gap and zero-energy surface Andreev bound states (Majorana fermions). A consequence of such Majorana fermions is a peak in the zero-energy density of states which should lead to a persistent zero-bias-conductance-peak (ZBCP) in Andreev reflection (AR) or tunneling experiments. Here we employ a newly developed nanoscale AR spectroscopy method to study normal metal/superconductor (N-S) devices featuring CuxBi2Se3. The results show that a ZBCP can be tuned in or out from CuxBi2Se3 samples depending on the N-S barrier strength. While the appearance of ZBCP may be traced to different origins, its absence under finite barrier strength represents the absence of zero-energy Majorana fermions. The present observations thus call for a reexamination of the nature of the superconducting state in CuxBi2Se3.