Strain-Induced Self Organization of Metal−Insulator Domains in Single-Crystalline VO 2 Nanobeams (original) (raw)
Related papers
Nature Nanotechnology, 2009
Correlated electron materials can undergo a variety of phase transitions, including superconductivity, the metal-insulator transition and colossal magnetoresistance 1 . Moreover, multiple physical phases or domains with dimensions of nanometres to micrometres can coexist in these materials at temperatures where a pure phase is expected 2 . Making use of the properties of correlated electron materials in device applications will require the ability to control domain structures and phase transitions in these materials. Lattice strain has been shown to cause the coexistence of metallic and insulating phases in the Mott insulator VO 2 . Here, we show that we can nucleate and manipulate ordered arrays of metallic and insulating domains along single-crystal beams of VO 2 by continuously tuning the strain over a wide range of values. The Mott transition between a low-temperature insulating phase and a high-temperature metallic phase usually occurs at 341 K in VO 2 , but the active control of strain allows us to reduce this transition temperature to room temperature. In addition to device applications, the ability to control the phase structure of VO 2 with strain could lead to a deeper understanding of the correlated electron materials in general.
Nano Letters, 2010
Formation of ferroelastic twin domains in vanadium dioxide (VO(2)) nanosystems can strongly affect local strain distributions, and hence couple to the strain-controlled metal-insulator transition. Here we report polarized-light optical and scanning microwave microscopy studies of interrelated ferroelastic and metal-insulator transitions in single-crystalline VO(2) quasi-two-dimensional (quasi-2D) nanoplatelets (NPls). In contrast to quasi-1D single-crystalline nanobeams, the 2D geometric frustration results in emergence of several possible families of ferroelastic domains in NPls, thus allowing systematic studies of strain-controlled transitions in the presence of geometrical frustration. We demonstrate the possibility of controlling the ferroelastic domain population by the strength of the NPl-substrate interaction, mechanical stress, and by the NPl lateral size. Ferroelastic domain species and domain walls are identified based on standard group-theoretical considerations. Using variable temperature microscopy, we imaged the development of domains of metallic and semiconducting phases during the metal-insulator phase transition and nontrivial strain-driven reentrant domain formation. A long-range reconstruction of ferroelastic structures accommodating metal-insulator domain formation has been observed. These studies illustrate that a complete picture of the phase transitions in single-crystalline and disordered VO(2) structures can be drawn only if both ferroelastic and metal-insulator strain effects are taken into consideration and understood.
Scientific reports, 2015
Single-crystalline vanadium dioxide (VO2) nanostructures have recently attracted great attention because of their single domain metal-insulator transition (MIT) nature that differs from a bulk sample. The VO2 nanostructures can also provide new opportunities to explore, understand, and ultimately engineer MIT properties for applications of novel functional devices. Importantly, the MIT properties of the VO2 nanostructures are significantly affected by stoichiometry, doping, size effect, defects, and in particular, strain. Here, we report the effect of substrate-mediated strain on the correlative role of thermal heating and electric field on the MIT in the VO2 nanobeams by altering the strength of the substrate attachment. Our study may provide helpful information on controlling the properties of VO2 nanobeam for the device applications by changing temperature and voltage with a properly engineered strain.
physica status solidi (RRL) - Rapid Research Letters, 2011
Vanadium dioxide undergoes a first order metalinsulator transition (MIT) from the high temperature metallic rutile (R) phase to an insulating monoclinic (M1) phase at a commercially accessible temperature. Two separate mechanisms have been proposed to explain the nature of the MIT: the Mott and Peierls mechanisms . Electron-electron interactions drive the MIT according to the Mott mechanism [3, 5] while the Peierls mechanism explains the transition in terms of electron -lattice interactions [1]. Between these two competing models, understanding the intermediate insulating M2 phase has been the most critical issue. The M2 phase of VO 2 is an electronic insulator despite band structure calculations suggesting that undimerized V atoms in the M2 phase should lead to conducting states . For this reason, the structural properties of the M2 phase prepared by applying stress or through Cr doping have been thoroughly investigated .
High-Strain-Induced Local Modification of the Electronic Properties of VO2 Thin Films
ACS Applied Electronic Materials
Vanadium dioxide (VO 2) is a popular candidate for electronic and optical switching applications due to its well-known semiconductor-metal transition. Its study is notoriously challenging due to the interplay of long and short range elastic distortions, as well as the symmetry change, and the electronic structure changes. The inherent coupling of lattice and electronic degrees of freedom opens the avenue towards mechanical actuation of single domains. In this work, we show that we can manipulate and monitor the reversible semiconductor-to-metal transition of VO 2 while applying a controlled amount of mechanical pressure by a nanosized metallic probe using an atomic force microscope. At a critical pressure, we can reversibly actuate the phase transition with a large modulation of the conductivity. Direct tunneling through the VO 2-metal contact is observed 1
Scientific reports, 2016
Mechanism of metal-insulator transition (MIT) in strained VO2 thin films is very complicated and incompletely understood despite three scenarios with potential explanations including electronic correlation (Mott mechanism), structural transformation (Peierls theory) and collaborative Mott-Peierls transition. Herein, we have decoupled coactions of structural and electronic phase transitions across the MIT by implementing epitaxial strain on 13-nm-thick (001)-VO2 films in comparison to thicker films. The structural evolution during MIT characterized by temperature-dependent synchrotron radiation high-resolution X-ray diffraction reciprocal space mapping and Raman spectroscopy suggested that the structural phase transition in the temperature range of vicinity of the MIT is suppressed by epitaxial strain. Furthermore, temperature-dependent Ultraviolet Photoelectron Spectroscopy (UPS) revealed the changes in electron occupancy near the Fermi energy EF of V 3d orbital, implying that the e...
Crystal Growth & Design, 2018
Vanadium dioxide (VO 2) nanowires/microbeams have attracted great interest recently because of their pronounced single-domain metal-insulator phase transition (MIT) behavior, which is promising for various device applications and deeper mechanism investigation. It is known that monoclinic VO 2 nanostructures can be effectively prepared by a simple thermal evaporation method, while the growth of dense and ordered VO 2 micro/nanowires with controlled crosssections is still a challenge. In the current study, we have selected different crystal facets as the growth template and achieved controllable growth of well-aligned VO 2 micro/nanowire arrays.