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Laboratory of Theoretical and Experimental Superconductive Tunnelling






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LaTEST is a section of the SMIM group (Superconductivity and Magnetism in Innovative Materials).
We carry out a (mainly fundamental) research in Solid State Physics, with particular focus on Superconductivity.

Fundamental study of unconventional superconductors

We investigate the fundamental properties of various classes of superconductors, mainly unconventional, by means of a  joint experimental-theoretical approach that involves:


  • point-contact Andreev-reflection spectroscopy  (down to 1.8 K, in magnetic field up to 9 T)
  • tunnel spectroscopy  (in break junctions or point-contact junctions, down to 4.2 K)
  • transport measurements (resistivity, sheet resistance, Hall effect,  down to 1.8 K and in magnetic fields up to 9 T)

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point contact scheme

  • ab-initio DFT calculations of the electronic bandstructure and of the Fermi surface [all-electron, full potential linearized augmented-plane wave (FP-LAPW) code]   
  • use of advanced models for the analysis of the Andreev-reflection spectra to extract quantitative information on the number, the amplitude and the symmetry of the superconducting gap (generalization of the BTK model to account for the real shape of the Fermi surface)

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Fermi surface

  • analysis / interpretation of the results within the Eliashberg theory (determination of the coupling strength, of the characteristic energy of the mediating boson, etc)
  • calculation of various physical quantities that can be compared to experiemental results  (penetration depth, critical fields, etc)

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Eliashberg calculations




Field-effect experiments

We study the effect of intense charge doping (induced by an electric field) on the conducting and superconducting properties of various materials (from metals to multilayer graphene).

This is achieved by fabricating "electric double layer" (EDL) field-effect transistors (FETs) based on a polymeric electrolyte solution that allows reaching extremely high densities of induced surface charge.

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FET photo




Advanced morphological and electrical characterization

We use atomic force microscopy (AFM) and scanning tunnel microscopy (STM) at room temperature for a morphological and electrical characterization of the surface, from a scale of 100 micrometers down to atomic scale.
Scanning tunnel spectroscopy (STS) can be used to build maps of local electrical conductivity.

Scanning thermal microscopy and nano thermal analysis are also available for the study of the local thermal conductivity (resolution of a few nm)  and of local temperature-dependent properties (thermal expansion, softening, melting) at the nanoscale.

In superconducting samples, point-contact Andreeev reflection spectroscopy or tunnel spectroscopy at low temperature can be used to map the local gap amplitudes and the local critical temperature (to be compared with that determined by transport).

AFM image

STS image


LaTEST - Department of Applied Science and Technology, Politecnico di Torino
corso Duca degli Abruzzi 24, 10129 Torino (TO) - Italy
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