Direct observation of quantum superconducting fluctuations in an insulating groundstate

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We review our recent measurements of the complex AC conductivity of thin InO_x films studied as a function of magnetic field through the nominal 2D superconductor-insulator transition. These measurements - the first of their type to probe nonzero frequency - reveals a significant finite frequency superfluid stiffness well into the insulating regime. Unlike conventional fluctuation superconductivity in which thermal fluctuations give a superconducting response in regions of parameter space that don't exhibit long range order, these fluctuations are temperature independent as T --> 0 and are exhibited in samples where the resistance is large (greater than 10^6 Ohms/Square) and strongly diverging. We interpret this as the direct observation of quantum superconducting fluctuations around an insulating ground state. This system serves as a prototype for other insulating states of matter that derive from superconductors.
Submitted to the proceedings of SCES07

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Superconductivity, Disordered Systems and Neural Networks

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http://salesiana.dossiersoluciones.com/handle/123456789/129742

Consulte el texto completo en el siguiente enlace:

https://arxiv.org/abs/0706.0144
 http://arxiv.org/abs/0706.0144

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arXiv