Origin of excess low-energy states in a disordered superconductor in a Zeeman field

Tunneling density of states measurements of disordered superconducting Al films in high Zeeman fields reveal a significant population of subgap states which cannot be explained by standard BCS theory. We provide a natural explanation of these excess states in terms of a novel disordered Larkin-Ovchi...

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Bibliographic Details
Published in:Physical review letters 2011-08, Vol.107 (6), p.067003-067003, Article 067003
Main Authors: Loh, Y L, Trivedi, N, Xiong, Y M, Adams, P W, Catelani, G
Format: Article
Language:English
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Summary:Tunneling density of states measurements of disordered superconducting Al films in high Zeeman fields reveal a significant population of subgap states which cannot be explained by standard BCS theory. We provide a natural explanation of these excess states in terms of a novel disordered Larkin-Ovchinnikov phase that occurs near the spin-paramagnetic transition at the Chandrasekhar-Clogston critical field. The disordered Larkin-Ovchinnikov superconductor is characterized by a pairing amplitude that changes sign at domain walls. These domain walls carry magnetization and support Andreev bound states that lead to distinct spectral signatures at low energy.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.107.067003