Synchronized charge oscillations in correlated electron systems

Abstract

Strongly correlated phases exhibit collective carrier dynamics that if properly harnessed can enable novel functionalities and applications. In this article, we investigate the phenomenon of electrical oscillations in a prototypical MIT system, vanadium dioxide (VO2). We show that the key to such oscillatory behaviour is the ability to induce and stabilize a non-hysteretic and spontaneously reversible phase transition using a negative feedback mechanism. Further, we investigate the synchronization and coupling dynamics of such VO2 based relaxation oscillators and show, via experiment and simulation, that this coupled oscillator system exhibits rich non-linear dynamics including charge oscillations that are synchronized in both frequency and phase. Our approach of harnessing a non-hysteretic reversible phase transition region is applicable to other correlated systems exhibiting metal-insulator transitions and can be a potential candidate for oscillator based non-Boolean computing.

Modeling and Simulation of Vanadium Dioxide Relaxation Oscillators

“…Discrete-component implementations of these VO 2 -based oscillators have been realized in the laboratory [11]. First attempts to couple and synchronize more VO 2 oscillators are currently under investigation [1], [13]. However, similarly to what has been done for MOSFET devices, as the VO 2 -based manufacturing process gets more mature, it becomes more apparent the need for developing circuit-level models of the new physical devices.…”

“…In the last few years, a great research effort has been spent in developing new fabrication processes, alternative to conventional CMOS, and targeted at the realization of compact and easy scalable nano-oscillators [1]- [3]. Such emerging technologies are expected to soon allow the large-scale integration of array of coupled oscillators paving the way to novel applications.…”

Modelling hysteresis in vanadium dioxide oscillators

“…Recently, it has been shown that connecting a VO 2 device with a resistor and a capacitor, of proper resistance and capacitance values, it is possible to fabricate very compact relaxation nano-oscillators [2]. The simple fabrication flow, the easy scalability with the possibility to achieve high packaging density, make VO 2 nano-oscillators promising candidates to integrate a large array of coupled oscillators for bio-inspired neurocomputing [2,3].…”

“…Recently, it has been shown that connecting a VO 2 device with a resistor and a capacitor, of proper resistance and capacitance values, it is possible to fabricate very compact relaxation nano-oscillators [2]. The simple fabrication flow, the easy scalability with the possibility to achieve high packaging density, make VO 2 nano-oscillators promising candidates to integrate a large array of coupled oscillators for bio-inspired neurocomputing [2,3].However, electrical measurements reveal that the switching-like behaviour of a two-terminal VO 2 comes at the expense of a hysteresis with the IMT and the MIT transition being driven by two different critical electric field values. In this Letter, we provide, for the first time, a circuit-level model of the hysteresis mechanism which is a key to predicting and controlling the dynamics of relaxation oscillators built on VO 2 devices.…”

Synchronization of two memristively coupled van der Pol oscillators

“…[20][21][22][23][24] In this letter we present our results on the (non-constant resistive) coupling of two self-sustained van der Pol oscillators via a memristive device. [2,[25][26][27][28] In this feasibility study we demonstrate an autonomous phase and frequency locking of the two oscillators (i.e. a transition from the asynchronous to a remnant synchronous state) due to the pulse dependent memristive coupling.…”