  We have measured the electrical properties of a V2O3 thin film micro bridge
at the insulator metal transition (IMT). Discontinuous jumps to lower voltages
in the current voltage characteristic (IV) followed by an approximately
constant voltage progression for high currents indicate an electrical breakdown
of the device. In addition, the IV curve shows hysteresis and a training
effect, i.e. the subsequent IV loops are different from the first IV loop after
thermal cycling. Low temperature scanning electron microscopy (LTSEM) reveals
that the electrical breakdown over the whole device is caused by the formation
of electro-thermal domains (ETDs), i.e. the current and temperature
redistribution in the device. On the contrary, at the nanoscale, the electrical
breakdown causes the IMT of individual domains. In a numerical model we
considered these domains as a network of resistors and we were able to
reproduce the electro-thermal breakdown as well as the hysteresis and the
training effect in the IVs.
