Interplay between electronic correlations and coherent structural dynamics during the monoclinic insulator-to-rutile metal phase transition in VO2

• Published in: Journal of physics. Condensed matter Vol. 23; no. 43; p. 435402
• Main Authors: Dachraoui, H, Müller, N, Obermeier, G, Oberer, C, Horn, S, Heinzmann, U
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 02.11.2011; Institute of Physics
• Subjects: Clean metal, semiconductor, and insulator surfaces; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electron and ion emission by liquids and solids; impact phenomena; Electron states; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Metal-insulator transitions and other electronic transitions; Photoemission and photoelectron spectra; Physics; Solid-solid transitions; Specific phase transitions; Photoelectron spectra; Energy gap; Electron correlations; Phase transformations; Metal-insulator transition; Vanadium oxide; Experimental device; Core levels; Time resolved spectra; Ultrafast process
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/23/43/435402

We report direct observations of the structural and electronic dynamics of the photoinduced insulator-metal transition in VO(2), by means of time-resolved photoemission spectroscopy. These observations provide new insights into the processes involved in this transition. Slightly above the threshold of the photoinduced phase transition, the different response times of the electrons and the lattice reveal the electronic nature of the band gap collapse. At high excitation densities, we find that the phase transition is induced nonthermally in an ultrashort time scale. Moreover, we identify different V 3p dynamics indicating the existence of different structural pathways. These results represent a clear demonstration of the potential of time-resolved core level photoelectron spectroscopy to study ultrafast dynamics in condensed matter.