Contact: Prof. Øystein Fischer (Director & Project leader of Project 6)

Team spring 2003

Resistive fault current limiter using YBa2Cu3O7 thin films grown on 2’’ saphire substrates.

Superconducting and Magnetic Properties of Complex Oxides
Materials with novel electronic properties are at the center of investigations in the various teams composing the group. A wide range of experimental facilities are dedicated to the synthesis of materials, the characterization of their electronic or structural properties and the fabrication of devices for technological applications.
Materials consist of epitaxial thin films, in the form of simple or heterostructures, deposited by magnetron sputtering (in near future also by laser ablation). The structural characterization is performed through x-ray diffraction and standard transport measurements are used to investigate the electronic properties of the compounds. Many of the materials studied are superconductors, with focus on the vortex phase diagram, inter and intralayer coupling, the effects of stress or of very high current densities, charge doping and intrinsic tunneling in highly anisotropic materials. Other unconventional materials like ferroelectrics or colossal magnetoresistance compounds are also under investigation.
Surface studies by scanning tunnelling microscopy are performed using both room temperature and very low temperature instruments (down to 0.3K). Studies are covering the in-situ investigations of thin film growth, nanolithography, potentiometry, spectroscopy of the electronic states of highly correlated electronic systems, charge doped systems with field effect, conventional and high temperature superconductors, together with the observation of vortices and spectroscopic measurements of the core states.
The use of superconducting thin films to fabricate fault current limiters is part of the global goal to develop technological applications using high temperature superconductors. The research is pushing this trend in collaboration with ABB towards the optimisation of device performances and the reduction of production costs.

References:
[1] M.R. Eskildsen et al., Phys. Rev. Lett. 89, 187003 (2002).
[2] S. Reymond et al., Phys. Rev. B 66, 14522 (2002).
[3] B. Grévin et al., Appl. Phys. Lett. 80, 3979 (2002).

Read the scientific article published in MaNEP Newsletter No. 3 (PDF 136 Ko)
Read a basic introduction to scanning probe microscopy