In many transition-metal oxides the electrical resistance is observed to undergo dramatic changes induced by large biases. In magnetite, Fe3 O4, below the Verwey temperature, an electric-field-driven transition to a state of lower resistance was recently found, with hysteretic current-voltage response. We report the results of pulsed electrical conduction measurements in epitaxial magnetite thin films. We show that while the high- to low-resistance transition is driven by electric field, the hysteresis observed in I-V curves results from Joule heating in the low-resistance state. The shape of the hysteresis loop depends on pulse parameters and reduces to a hysteresis-free "jump" of the current provided thermal relaxation is rapid compared to the time between voltage pulses. A simple relaxation-time thermal model is proposed that captures the essentials of the hysteresis mechanism.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Jun 26 2009|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics