Infrared spectroscopy and nano-imaging of the insulator-to-metal transition in vanadium dioxide
Autor: | M. Mumtaz Qazilbash, Oleg Shpyrko, Byung-Gyu Chae, Sun Jin Yun, Alexander V. Balatsky, Gregory O. Andreev, M. Brehm, Alex Frenzel, Dimitri Basov, Bong-Jun Kim, M. B. Maple, Fritz Keilmann, Pei-Chun Ho, Hyun-Tak Kim |
---|---|
Rok vydání: | 2009 |
Předmět: |
Condensed Matter - Materials Science
Phase transition Materials science Strongly Correlated Electrons (cond-mat.str-el) Condensed matter physics Infrared business.industry Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences Infrared spectroscopy Condensed Matter Physics Electronic Optical and Magnetic Materials law.invention Condensed Matter - Strongly Correlated Electrons Effective mass (solid-state physics) Optics Optical microscope law Condensed Matter::Strongly Correlated Electrons Strongly correlated material Metal–insulator transition Infrared microscopy business |
Zdroj: | Physical Review B. 79 |
ISSN: | 1550-235X 1098-0121 |
Popis: | We present a detailed infrared study of the insulator-to-metal transition (IMT) in vanadium dioxide (VO2) thin films. Conventional infrared spectroscopy was employed to investigate the IMT in the far-field. Scanning near-field infrared microscopy directly revealed the percolative IMT with increasing temperature. We confirmed that the phase transition is also percolative with cooling across the IMT. We present extensive near-field infrared images of phase coexistence in the IMT regime in VO2. We find that the coexisting insulating and metallic regions at a fixed temperature are static on the time scale of our measurements. A novel approach for analyzing the far-field and near-field infrared data within the Bruggeman effective medium theory was employed to extract the optical constants of the incipient metallic puddles at the onset of the IMT. We found divergent effective carrier mass in the metallic puddles that demonstrates the importance of electronic correlations to the IMT in VO2. We employ the extended dipole model for a quantitative analysis of the observed near-field infrared amplitude contrast and compare the results with those obtained with the basic dipole model. 18 pages including 8 figures |
Databáze: | OpenAIRE |
Externí odkaz: |