Current-induced switching from metallic to insulating state is observed in phase-separated states of (La_{1-y}Pr_y)_{0.7}Ca_{0.3}MnO_3 (y=0.7) and Nd_{0.5}Ca_{0.5}Mn_{1-z}Cr_zO_3 (z=0.03) crystals. Application of magnetic fields to this current-induced insulating state causes pronounced low-field negative magnetoresistance effect [r(H)/r(0)=10^{-3} at H=1kOe]. Application of a constant voltage also causes breakdown of ohmic relation above a threshold voltage. At voltages higher than this threshold value, oscillations in currents are observed. This oscillation is well reproduced by a simple model of local switching of a percolative conduction path.
@article{arxiv.cond-mat/0504128,
title = {Current oscillation and low-field colossal magnetoresistance effect in phase-separated manganites},
author = {M. Tokunaga and H. Song and Y. Tokunaga and T. Tamegai},
journal= {arXiv preprint arXiv:cond-mat/0504128},
year = {2009}
}
Comments
5 pages, 4 figures, to be published in Physical Review Letters