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Evidence of a second-order Peierls-driven metal-insulator transition in crystalline NbO 2

DOI: 10.1103/PhysRevMaterials.3.074602 DOI Help

Authors: Matthew J. Wahila (Binghamton University) , Galo Paez (Binghamton University) , Christopher N. Singh (Binghamton University) , Anna Regoutz (Imperial College London) , Shawn Sallis (Binghamton University) , Mateusz J. Zuba (Binghamton University) , Jatinkumar Rana (Binghamton University) , M. Brooks Tellekamp (Georgia Institute of Technology) , Jos E. Boschker (Leibniz-Institut für Kristallzüchtung) , Toni Markurt (Leibniz-Institut für Kristallzüchtung) , Jack E. N. Swallow (University of Liverpool) , Leanne A. H. Jones (University of Liverpool) , Tim D. Veal (University of Liverpool) , Wanli Yang (Advanced Light Source) , Tien-lin Lee (Diamond Light Source) , Fanny Rodolakis (Argonne National Laboratory) , Jerzy T. Sadowski (Brookhaven National Laboratory) , David Prendergast (Lawrence Berkeley National Laboratory) , Wei-cheng Lee (Binghamton University) , W. Alan Doolittle (Georgia Institute of Technology) , Louis F. J. Piper (Binghamton University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Materials , VOL 3

State: Published (Approved)
Published: July 2019
Diamond Proposal Number(s): 20647 , 21430

Abstract: The metal-insulator transition of NbO 2 is thought to be important for the functioning of recent niobium oxide-based memristor devices, and is often described as a Mott transition in these contexts. However, the actual transition mechanism remains unclear, as current devices actually employ electroformed NbO x that may be inherently different to crystalline NbO 2 . We report on our synchrotron x-ray spectroscopy and density-functional-theory study of crystalline, epitaxial NbO 2 thin films grown by pulsed laser deposition and molecular beam epitaxy across the metal-insulator transition at ∼ 810 ∘ C . The observed spectral changes reveal a second-order Peierls transition driven by a weakening of Nb dimerization without significant electron correlations, further supported by our density-functional-theory modeling. Our findings indicate that employing crystalline NbO 2 as an active layer in memristor devices may facilitate analog control of the resistivity, whereby Joule-heating can modulate Nb-Nb dimer distance and consequently control the opening of a pseudogap.

Journal Keywords: Composition; Crystal structure; Density of states; Electrical conductivity; First-principles calculations; Metal-insulator transition; Peierls transition; Phase transitions; Second order phase transitions; Structural phase transition

Subject Areas: Materials, Physics

Instruments: I09-Surface and Interface Structural Analysis