Enhancement of superconductivity by a parallel magnetic field in two-dimensional superconductors

Superconductivity is a quantum state of matter characterized by the formation of Cooper pairs from time-reversal-symmetric electronic states. Mechanisms that break this symmetry, such as magnetic-impurity scattering and applied magnetic fields, are expected to be detrimental to superconductivity and...

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Bibliographic Details
Published in:Nature physics 2011-11, Vol.7 (11), p.895-900
Main Authors: Jeffrey Gardner, H., Kumar, Ashwani, Yu, Liuqi, Xiong, Peng, Warusawithana, Maitri P., Wang, Luyang, Vafek, Oskar, Schlom, Darrell G.
Format: Article
Language:English
Subjects:
Atomic
Classical and Continuum Physics
Complex Systems
Condensed Matter Physics
Film thickness
Lead (metal)
Magnetic fields
Mathematical and Computational Physics
Molecular
Optical and Plasma Physics
Physics
Physics and Astronomy
Quantum theory
Radicals
Superconductivity
Superconductors
Symmetry
Theoretical
Transition temperature (superconductivity)
Two dimensional
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Summary:Superconductivity is a quantum state of matter characterized by the formation of Cooper pairs from time-reversal-symmetric electronic states. Mechanisms that break this symmetry, such as magnetic-impurity scattering and applied magnetic fields, are expected to be detrimental to superconductivity and suppress the critical temperature. Here, we report the observation of pronounced increases in the mean-field critical temperature on application of a parallel magnetic field in two different two-dimensional superconducting systems: ultrathin, homogeneously disordered amorphous Pb films and the two-dimensional electron gas at the interface of LaAlO 3 and SrTiO 3 . In the amorphous Pb films, the critical-temperature increases exhibit a systematic dependence on the film thickness. Significantly, the presence of paramagnetic impurities in the films diminishes the effect of field enhancement of superconductivity. These observations mark a radical departure from the current understanding of the interactions between magnetic fields and superconductivity. Superconductivity and magnetism have often been regarded as opposites. High magnetic fields usually destroy the superconducting state. But for superconductors constrained to two dimensions, a parallel magnetic field can actually enhance superconductivity.
ISSN:1745-2473
1745-2481
DOI:10.1038/nphys2075