Orateur
Description
Two-dimensional superconductors confront physicists with new challenges by exhibiting a wide variety of unconventional behaviors not captured by the BCS theory. In particular, two-dimensional superconductors are expected to show signs of the Berezinksi-Kosterlitz-Thouless transition (BKT) in their superconducting properties such as resistivity and superfluid stiffness. The cuprate family compounds share a common layered crystal structure with two-dimensional superconducting CuO2 planes interacting with charge storage layers. Among the various cuprates, BiSrCaCuO (BSCCO-2212) is particularly interesting to address the issue of 2D superconductivity. Because it has a natural cleavage plane between the BiO planes, this material can be exfoliated down to 1u.c using the standard scotch-tape exfoliation method [1]. Surprisingly, the 1u.c. thick layer maintains a superconducting critical temperature very similar to that of the bulk material. In 2017, Sterpetti et al [2] reported an electrostatic doping method to explore the electronic phase diagram of exfoliated 2D BSCCO-2212 flakes. Their DC transport measurements showed the influence of doping on both on the superconducting transition temperature (Tc) and the crossover temperatures separating the different regions in the normal state (pseudogap, strange metal and Fermi liquid phases). However, no electrodynamic property of 2D exfoliated superconducting BSCCO-2212 has been investigated so far.
In this talk, I will discuss the fabrication and measurement of 2D BSCCO-2212 1u.c flakes in both DC and microwave regime. Our DC resistivity curves are consistent with the work of Sterpetti et al. and our analysis of I-V curves suggests some evidence of BKT physics, which we have further investigated in the microwave frequency range through transmission measurements. The complex conductivity of the BSCCO-2212 1u.c flakes in the [1GHz,20GHz] has been extracted as a function of temperature. The superfluid stiffness derived from the imaginary part of the conductivity shows a jump near Tc, which is the expected hallmark of the BKT transition. A peak in the real part of the complex conductivity is simultaneously observed, which we associate with the dissociation of the vortex-antivortex pairs.
[1]Novoselov, Kostya S., et al. science 306.5696 (2004): 666-669.
[2] Sterpetti, Edoardo, et al. Nature communications 8.1 (2017): 2060.
| Affiliation de l'auteur principal | UMR 8213 Laboratory of Physics and Material studies ESPCI Paris, CNRS, UPMC, PSL University, 10 Rue Vauquelin, 75 005 Paris |
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