Ultrafast response of photoexcited carriers in VO2 at high-pressure. (2nd August 2018)

• Record Type: Journal Article
• Authors: Braun, Johannes M; Schneider, Harald; Helm, Manfred; Mirek, Rafał; Boatner, Lynn A; Marvel, Robert E; Haglund, Richard F; Pashkin, Alexej
• Is Part Of: New journal of physics. Volume 20:Number 8(2018:Aug.)
• Publication Date: 2018-08-02
• Subjects: metal–insulator transition -- vanadium dioxide -- ultrafast spectroscopy -- high-pressure; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/aad4ef
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: We utilize near-infrared pump—mid-infrared probe spectroscopy to investigate the ultrafast electronic response of pressurized VO2 . A clear anomaly in the linear mid-infrared response as well as in the fluence dependence of the pump–probe signal is observed around 8 GPa indicating a pressure-induced phase transition. Distinct pump–probe signals and a pumping threshold behavior typical for the insulating VO2 phase persist also in the high-pressure phase. Thus, in contrast to the temperature-induced rutile metallic state of VO2, the pressure-induced monoclinic phase preserves the energy gap. However, our results indicate the appearance and a gradual growth of additional intragap states upon increasing pressure above 8 GPa. These observations can be interpreted in terms of a bandwidth-controlled Mott–Hubbard transition.