Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session T60: Poster Session III
Thursday, March 8, 2018
LACC Room: West Hall A
Abstract: T60.00137 : Current-controlled-negative-differential-resistivity, insulator to mixed metal-insulator state switching and power dissipation in self-heated VO2 single crystals.
The outstanding features of the insulator-metal-transition (IMT) in VO2 at TIMT=340 K include a large negative thermal emissivity in the infrared over the transition. Under an applied current, the resistance drops due to Joule heating, the voltage reaches a maximum and a current controlled negative differential resistivity (CC-NDR) regime sets on. The mixed insulator-metal phase appears within the NDR regime. The stability of I(V) of a sample in this regime is governed by the load resistance (RL) in series with the sample. For small enough RL the sample switches from the last steady state with maximal Joule heating power (Pmax) to a state with minimal Joule heating power (Pmin). Instead of hot filaments that are formed upon switching in thin films, the mixed state of single crystals consists of dynamic or static metal-insulator domains with boundaries that cross the width of the crystal at favorable inclinations. The results derived from I-V characteristics of several VO2 single crystals show that: 1. Pmax / Pmin may exceed by far the ratio between the emissivity in the infrared of the insulator to that of the metal and 2. Beyond the minimum, P increases with increasing current due to sliding domains but this increase as well as sliding are suppressed by damage.
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