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Direct observation of quantum superconducting fluctuations across the 2D superconductor-insulator transition

✍ Scribed by N.P. Armitage; R.W. Crane; G. Sambandamurthy; A. Johansson; D. Shahar; V. Zaretskey; G. Grüner

Publisher
Elsevier Science
Year
2008
Tongue
English
Weight
158 KB
Volume
403
Category
Article
ISSN
0921-4526

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✦ Synopsis

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 to probe anything other than the o ¼ 0 response of these archetypical systems-reveal a significant finite frequency superfluid stiffness well into the insulating regime. Unlike conventional fluctuation superconductivity in which thermal fluctuations can give a superconducting response in regions of parameter space that do not 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 O=&) and strongly diverging. We interpret this as the first 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.

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