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arXiv · 1301.1030

Absence of zero-energy surface bound states in CuxBi2Se3 via a study of Andreev reflection spectroscopy

Haibing Peng·Debtanu De·Bing Lv·Fengyan Wei·Ching-Wu Chu
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Abstract

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.

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Haibing Peng, Debtanu De, Bing Lv, Fengyan Wei, Ching-Wu Chu. 2013-01-06. Absence of zero-energy surface bound states in CuxBi2Se3 via a study of Andreev reflection spectroscopy. https://doi.org/10.1103/physrevb.88.024515

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