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 predicted 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 CuxBi 2Se3. 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 intriguing superconductivity in CuxBi 2Se3.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2013 Jul 25|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics