2007/06/01 by N. P. Armitage, Armitage, N. P., R. Crane +9
Physics and Astronomy · #Disordered Systems and Neural Networks (cond-mat.dis-nn) #FOS: Physical sciences #Superconductivity (cond-mat.supr-con) #cond-mat.dis-nn #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.0706.0144
Submitted to the proceedings of SCES07
arxiv created 2007/06/01 · arxiv updated 2009/12/01
We review our recent measurements of the complex AC conductivity of thin InOx 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 106 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.