In situ band gap mapping of the V2O5(001) crystal surface revealed a reversible metal-to-insulator transition at 350-400 K, which occurs inhomogeneously across the surface and expands preferentially in the direction of the vanadyl (V=O) double rows. Supported by density functional theory and Monte Carlo simulations, the results are rationalized on the basis of the anisotropic growth of vanadyl-oxygen vacancies and a concomitant oxygen loss driven metal-to-insulator transition at the surface. At elevated temperatures irreversible surface reduction proceeds sequentially as V2O5(001) --> V6O13(001) --> V2O3(0001).
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http://dx.doi.org/10.1103/PhysRevLett.99.226103 | DOI Listing |
NPJ Comput Mater
January 2025
Computational Atomic-scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, Kgs. Lyngby, Denmark.
We conduct a systematic investigation of the role of Hubbard U corrections in electronic structure calculations of two-dimensional (2D) materials containing 3 transition metals. Specifically, we use density functional theory (DFT) with the PBE and PBE+U approximations to calculate the crystal structure, band gaps, and magnetic parameters of 638 monolayers. Based on a comprehensive comparison to experiments we first establish that the inclusion of the U correction worsens the accuracy for the lattice constants.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Terahertz Research Center, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
Low-dimensional materials (LDMs) with unique electromagnetic properties and diverse local phenomena have garnered significant interest, particularly for their low-energy responses within the terahertz (THz) range. Achieving deep subwavelength resolution, THz nanoscopy offers a promising route to investigate LDMs at the nanoscale. Steady-state THz nanoscopy has been demonstrated as a powerful tool for investigating light-matter interactions across boundaries and interfaces, enabling insights into physical phenomena such as localized collective oscillations, quantum confinement of quasiparticles, and metal-to-insulator phase transitions (MITs).
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
Center for High Pressure Science & Technology Advanced Research (HPSTAR), Shanghai, 201203, P.R. China.
Under extreme conditions, condensed matters are subject to undergo a phase transition and there have been many attempts to find another form of hydroxide stabilized over HO. Here, using Density Functional Theory (DFT)-based crystal structure prediction including zero-point energy, it is that proton superoxide (HO), the lightest superoxide, can be stabilized energetically at high pressure and temperature conditions. HO is metallic at high pressure, which originates from the 𝜋 orbitals overlap between adjacent superoxide anions (O ).
View Article and Find Full Text PDFNanoscale
December 2024
Layered Materials and Device Physics Laboratory, Department of Chemistry, Physics and Atmospheric Science, Jackson State University, Jackson, MS 39217, USA.
The metal-to-insulator phase transition (MIT) in two-dimensional (2D) materials under the influence of a gating electric field has revealed interesting electronic behavior and the need for a deeper fundamental understanding of electron transport processes, while attracting much interest in the development of next-generation electronic and optoelectronic devices. Although the mechanism of the MIT in 2D semiconductors is a topic under debate in condensed matter physics, our work demonstrates the tunable percolative phase transition in few-layered MoSe field-effect transistors (FETs) using different metallic contact materials. Here, we attempted to understand the MIT through temperature-dependent electronic transport measurements by tuning the carrier density in a MoSe channel under the influence of an applied gate voltage.
View Article and Find Full Text PDFNanoscale
January 2025
Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Sector III, Block JD, Salt Lake, Kolkata 700106, India.
Creating van der Waals (vdW) homojunction devices requires materials with narrow bandgaps and high carrier mobilities for bipolar transport, which are crucial for constructing fundamental building blocks like diodes and transistors in a 2D architecture. Following the recent discovery of elemental 2D tellurium, here, we systematically investigate the electrical transport and flicker noise of hydrothermally grown multilayer tellurium field effect transistors. While the devices exhibit a dominant p-type behavior with high hole mobilities up to ∼242 cm V s at room temperature and almost linear current-voltage characteristics down to 77 K, ambipolar behavior was observed in some cases.
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