Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 73: Correlated Electrons: Nonequilibrium Quantum Many-Body Systems 2
TT 73.7: Vortrag
Donnerstag, 23. März 2017, 16:45–17:00, HSZ 304
The nature of the pressure-induced metallization in VO2 — •Johannes M. Braun1,2, Harald Schneider1, Manfred Helm1,2, Rafał Mirek3, Lynn A. Boatner4, Robert E. Marvel5, Richard F. Haglund5, and Alexej Pashkin1 — 1Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — 2TU Dresden, Germany — 3University of Warsaw, Poland — 4Oak Ridge National Laboratory, USA — 5Vanderbilt University, Nashville, USA
We utilize ultrafast optical pump – THz probe spectroscopy in order to investigate the pressure-driven insulator-to-metal transition (IMT) in vanadium dioxide (VO2). The probe pulses with central frequency of 30 THz enable a sensitive detection of the photoinduced metallization.
The threshold pump fluence necessary for generation of a metastable metallic phase has been systematically measured for pressures up to 19 GPa. Initial pressure application leads to a notable increase of the threshold fluence. This contrasts the thermally-driven IMT in VO2 where it decreases on approaching the transition temperature. Above the IMT, that occurs at approximately 6–8 GPa, we observe a sharp drop of the threshold fluence. However, the clear threshold behavior characteristic for systems with cooperative electronic localization still could be observed also in the metallic state up to the highest applied pressure.
Our results support a view of the pressure-induced IMT in VO2 as a purely electronic bandwidth-driven Mott-Hubbard transition, that does not involve any change in the crystal structure.