LAUSR

We report an asymmetry in the R vs T characteristics across the first order metalinsulator transition (MIT) of V2O3 nanowires. The resistance changes in a few, large jumps during cooling through the MIT, while it does it in a smoother way during warming. The asymmetry is greatly enhanced as the width of the nanowire approaches a characteristic domain size. Our results, together with previous reports in VO2 [1] and FeRh [2] imply that asymmetry is a generic feature of first order phase transitions in 1D systems. We show that this behavior is a simple, elegant consequence of the combined effects of the transition hysteresis and the temperature dependence of the insulating gap in this case (and generically, the order parameter relevant for the physical observable). We conclude that our proposed asymmetry mechanism is universally applicable to many electronic first order phase transitions.