Scaling analysis of an apparent metal-insulator transition in a Fe3O4/Nb:SrTiO3 bilayer

Journal of Magnetism and Magnetic Materials 316, e674 (2007)
Proceedings of the Joint European Magnetic Symposia

Y.F. Chen, M. Ziese and P. Esquinazi


Magnetite films were deposited on Nb-doped SrTiO3 substrates by pulsed laser deposition. The current–voltage characteristics were measured perpendicular to the interface. Strongly nonlinear, asymmetric current–voltage curves were observed. The resistance shows a crossover from insulating to metallic behavior for increasing voltages. The data can be neatly scaled using a scaling approach based on a quantum critical transition theory. This shows that a scaling analysis is clearly insufficient to conclude on the existence of a bulk-like metal/superconductor–insulator transition.