We have grown epitaxial Cr-doped V2O3 thin films with Cr concentrations between 0 and 20% on (0001)-Al2O3 by oxygen-assisted molecular beam epitaxy. For the highly doped samples (> 3%), a regular and monotonous increase of the resistance with decreasing temperature is measured. Strikingly, in the low doping samples (between 1% and 3%), a collapse of the insulating state is observed with a reduction of the low temperature resistivity by up to 5 orders of magnitude. A vacuum annealing at high temperature of the films recovers the low temperature insulating state for doping levels below 3% and increases the room temperature resistivity towards the values of Cr-doped V2O3 single crystals. It is well-know that oxygen excess stabilizes a metallic state in V2O3 single crystals. Hence, we propose that Cr doping promotes oxygen excess in our films during deposition leading to the collapse of the low temperature insulating state at low Cr concentrations. These results suggest that slightly Cr-doped V2O3 films can be interesting candidates for field effect devices.
@article{arxiv.1509.05866,
title = {Collapse of the low temperature insulating state in Cr-doped V$_2$O$_3$ thin films},
author = {Pía Homm and Leander Dillemans and Mariela Menghini and Bart Van Bilzen and Petar Bakalov and Chen-Yi Su and Ruben Lieten and Michel Houssa and Davoud Nasr Esfahani and Lucian Covaci and Francois Peeters and Jin Won Seo and Jean-Pierre Locquet},
journal= {arXiv preprint arXiv:1509.05866},
year = {2015}
}