Speaker
Prof.
Elvezio Morenzoni
(Paul Scherrer Institut)
Description
The Meissner effect and the associated perfect bulk diamagnetism are, besides zero resistance and gap opening, characteristic features of the superconducting state. In the pseudogap phase of cuprates unusual diamagnetic signals as well as anomalous proximity effects have been detected but a Meissner effect has never been observed. Here, we have probed by low energy muSR the local diamagnetic response in the normal state of an underdoped (UD) La_1.94Sr_0.06CuO_4 layer (up to 46 nm thick, critical temperature Tc'< 5 K) brought in close contact with two nearly optimally doped (OP) La_1.84Sr_0.16CuO_4 layers Tc = 32 K. We show that the entire barrier layer of thickness much larger than typical c-axis coherence lengths of cuprates exhibits Meissner effect for temperatures well above Tc' but below Tc. We determine the temperature dependence of the effective penetration depth and superfluid density in the different layers. The results indicate that superfluidity with long-range phase coherence is induced in the underdoped layer by the proximity of optimally doped layers; however, this order is very sensitive to thermal excitation.
E. Morenzoni et al., Nat. Commun. 2, 272, 2011.
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Multiple Order Parameter
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Primary author
Prof.
Elvezio Morenzoni
(Paul Scherrer Institut)
Co-authors
Dr
Andreas Suter
(Paul Scherrer Institut)
Dr
Bastian Wojek
(Paul Scherrer Institut and University Zürich)
Dr
Gennady Logvenov
(Brookhaven National Laboratory)
Prof.
Ivan Bozovic
(Brookhaven National Laboratory)
Dr
Thomas Prokscha
(Paul Scherrer Institut)
