Embedded metallic nanoparticles facilitate metastability of switchable metallic domains in Mott threshold switches

Abstract

Mott threshold switching, which is observed in quantum materials featuring an electrically fired insulator-to-metal transition, calls for delicate control of the percolative dynamics of electrically switchable domains on a nanoscale. Here, we demonstrate that embedded metallic nanoparticles (NP) dramatically promote metastability of switchable metallic domains in single-crystal-like VO2 Mott switches. Using a model system of Pt-NP-VO2 single-crystal-like films, interestingly, the embedded Pt NPs provide 33.3 times longer ‘memory’ of previous threshold metallic conduction by serving as pre-formed ‘stepping-stones’ in the switchable VO2 matrix by consecutive electical pulse measurement; persistent memory of previous firing during the application of sub-threshold pulses was achieved on a six orders of magnitude longer timescale than the single-pulse recovery time of the insulating resistance in Pt-NP-VO2 Mott switches. This discovery offers a fundamental strategy to exploit the geometric evolution of switchable domains in electrically fired transition and potential applications for non-Boolean computing using quantum materials.

Controllable Phase Transition Properties in VO2Films via Metal-Ion Intercalation

“…The bump in the curve is likely because of the inhomogeneous phase transition within the VO 2 film: i.e., both metallic and insulating phases coexist in an inhomogeneous transitional state. A similar irregular transition (e.g., more than one endothermic/exothermic peak during the heating/cooling cycle) has been previously reported, which was attributed to the dispersive size distribution of Ti x V 1– x O 2 or percolated Pt nanoparticles in VO 2 films in previous cases . The underlying mechanism will be discussed in detail in a later section.…”

“…A similar irregular transition (e.g., more than one endothermic/ exothermic peak during the heating/cooling cycle) has been previously reported, which was attributed to the dispersive size distribution of Ti x V 1−x O 2 26 or percolated Pt nanoparticles in VO 2 films in previous cases. 29 The underlying mechanism will be discussed in detail in a later section. It is possibly due to irregular percolation of switchable metallic domains resulting from partial intercalation within the VO 2 matrix.…”

Piezo strain–controlled phase transition in single-crystalline Mott switches for threshold-manipulated leaky integrate-and-fire neurons

“…The discovery of quantum materials featuring metal-insulator transition (MIT) has prompted efforts to control the reversible phase transition by applying external stimuli to overcome the limitations of current electronic devices (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). As an archetypical quantum material with an MIT, VO 2 undergoes abrupt MIT upon more than three orders of magnitude of electrical-conductance modulation, along with submicrosecond transition time (1, 2, 4-6, 9, 10).…”

“…The discovery of quantum materials featuring metal-insulator transition (MIT) has prompted efforts to control the reversible phase transition by applying external stimuli to overcome the limitations of current electronic devices ( 1 – 10 ). As an archetypical quantum material with an MIT, VO 2 undergoes abrupt MIT upon more than three orders of magnitude of electrical-conductance modulation, along with submicrosecond transition time ( 1 , 2 , 4 – 6 , 9 , 10 ). By using these exotic material functionalities, two-terminal devices can cause a voltage-triggered insulator-to-metal transition (i.e., threshold switching), thereby sensing the multiple states of electrical conductance of VO 2 by controlling the magnitude and time interval of voltage stimuli ( 1 , 4 – 6 , 9 , 10 ).…”

“…As an archetypical quantum material with an MIT, VO 2 undergoes abrupt MIT upon more than three orders of magnitude of electrical-conductance modulation, along with submicrosecond transition time ( 1 , 2 , 4 – 6 , 9 , 10 ). By using these exotic material functionalities, two-terminal devices can cause a voltage-triggered insulator-to-metal transition (i.e., threshold switching), thereby sensing the multiple states of electrical conductance of VO 2 by controlling the magnitude and time interval of voltage stimuli ( 1 , 4 – 6 , 9 , 10 ). Thus, stimuli-dependent conductance modulation enables two-terminal VO 2 threshold switches to emulate the function of neurons as an ultracompact artificial neuron ( 1 , 4 , 5 , 11 – 13 ).…”