2026-09-22T19:06:17Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/23160 2023-07-10 col_2142_5131 col_2142_8859 com_2142_5130 com_2142_8858 com_2142_234

Van Harlingen, Dale J. Tessmer, Stuart Holden 2011-05-07T14:04:18Z 2011-05-07T14:04:18Z 10000-01-01 1995 In this work we consider systems in which small normal-metal structures (N) are put into contact with a large superconductor (S), with the goal of spatially characterizing the superconductivity. Confined regions with suppressed superconductivity will support quasiparticle bound states, which can be measured spectroscopically. Using a custom-built cryogenic scanning tunneling microscopy system, we have probed the bound states of an NS system consisting of Au (N) droplets of nanometer dimensions in electrical contact with bulk NbSe$\sb 2$ (S). A quasiparticle bound state was observed even when tunneling directly into the NbSe$\sb 2$, clear evidence for a significant reduction of the superconductivity inside the NbSe$\sb 2$ induced by the proximity of the Au over-layer. By invoking a proximity effect model, we are able to characterize the vertical and lateral variation of the pair potential $\Delta$ inside the superconductor. We find that a severe suppression occurs which is beyond the conventional theory. We believe that this effect arises from the short coherence length of the superconductor, so that the spatial variation of the interaction parameter g becomes important. The profile of $\Delta$ that we extract from our data then combines both the conventional proximity suppression of $\Delta$ and its modulation by the profile of g, representing the first observation of spatial structure of the interaction parameter. Made available in DSpace on 2011-05-07T14:04:18Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9624511.pdf: 3305979 bytes, checksum: cce37c09c20afa7a1cda66bce706fee0 (MD5) Previous issue date: 1995 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T15:02:35Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:29:46-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9624511 (UMI)AAI9624511 http://hdl.handle.net/2142/23160 eng Copyright 1995 Tessmer, Stuart Holden Physics, Electricity and Magnetism Physics, Condensed Matter Quasiparticle bound states in normal metal/superconductor structures probed by scanning tunneling microscopy text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.