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Summary: Condensed Matter Colloquium
Thursday, April 14, 2011
2 pm, Room 1201
Refreshments at 1:30 pm in Room 1305F
Benjamin Sacépé
Institut Néel, CNRS & Université Joseph Fourier,
Grenoble, France
Localization of Cooper-pairs in disordered superconductors
The concept of localized Cooper pairs in disordered superconducting films close to the
Superconductor-Insulator Transition (SIT) has intrigued scientists for several decades
both theoretically and experimentally. Although localization and superconductivity are
clearly evidenced on the macroscopic scale by transport measurements, very little is
known about the microscopic details of their interplay. In this talk I will present tunneling
measurements of the local density-of-states on amorphous indium oxide films close to the
SIT [1]. Our results show that disorder fluctuations lead to a mixture of superconducting
and insulating regions that distinguish themselves by the presence or absence of
coherence peaks at the gap edges. Besides, using our STM, we have continuously
analyzed the local conductance between the tunneling regime and the point-contact
regime. In the latter, Andreev spectroscopy reveals a new energy scale related to the
quantum coherence energy and independent from spatial fluctuations of the pairing
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