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Ultrafast response of photoexcited carriers in VO₂ at high-pressure

Braun, J. M.; Schneider, H.; Helm, M.; Mirek, R.; Boatner, L. A.; Marvel, R. E.; Haglund Jr., R. F.; Pashkin, A.

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.

Keywords: metal-insulator transition; vanadium dioxide; ultrafast spectroscopy; high-pressure

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Permalink: https://www.hzdr.de/publications/Publ-27283
Publ.-Id: 27283