Anomalous density of states in hybrid normalmetal–superconductor bilayers

Pramana

A K Gupta1²  L Crétinon¹  B Pannetier¹  H Courtois¹ 

[1] Centre de Recherches sur les Très Basses Températures - C.N.R.S. associé à l'Université Joseph Fourier, 25 Avenue des Martyrs, 38042 Grenoble, France$$;Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016, India$$

关键词: Proximity effect;    density of states;    Andreev reflection.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

In contact with a superconductor, the Andreev reflection of the electronslocally modifies the N metal electronic properties, including the local density of states(LDOS). We investigated the LDOS in superconductor–normal metal (Nb–Au) bilayersusing a very low temperature (60 mK) STM on the normal metal side. High resolutiontunneling spectra measured on the Au surface show a clear proximity effect with an energygap of reduced amplitude compared to the bulk Nb gap. The dependence of this mini-gap width with the normal metal thickness is discussed in terms of the Thouless energy. Within the mini-gap, the density of states does not reach zero and shows clear sub-gapfeatures. We compare the experimental spectra with the well-established quasi-classicaltheory.

【 授权许可】

Unknown