Resistive switching in Sr1−0.05La0.05TiO3

The analysis of the electronic structure of La doped SrTiO₃ single crystals, Sr_1-xLa_xTiO₃ with x=5 at % (SLTO), shows that additional electrons in the host matrix are accommodated by a change of the valence of Ti ions from Ti⁺⁴ to Ti⁺³. We found, however, no evidence of a metallic peak near the Fermi level by electron spectroscopy. Similarly, electrical characterisation of the material revealed only semiconducting behaviour. This stands in contrast to the general idea of a macroscopic insulator-to-metal transition in SLTO at a doping level of a few percent of La. By means of conducting AFM we found evidence of an inhomogeneity of the in plane conductivity at the nano-scale and the possibility of locally manipulating the electric resistivity by means of an electrical stimuli, i.e. resistive switching. The observed inhomogeneity is attributed to a non-uniform distribution of La doping and a high density of extended defects in SLTO crystal.