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Title: Evidence for impact ionization in vanadium dioxide

Pump-probe optical spectroscopy was used to investigate charge carrier multiplication via impact ionization in the M1 insulating phase of VO2. By comparing the transient reflectivities of the film when pumped at less than and then more than twice the band-gap energy, we observed an enhancement of the ultrafast response with the higher energy pump color while the film was still transiently in the insulating phase. We additionally identified multiple timescales within the charge dynamics and analyzed how these changed when the pump and probe wavelengths were varied. This experiment provided evidence that impact ionization acts efficiently as a carrier multiplication process in this prototypical strongly-correlated insulator.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [1] ;  [2]
  1. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Florida State Univ., Tallahassee, FL (United States). Dept. of Physics
  2. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
Publication Date:
OSTI Identifier:
1339356
Grant/Contract Number:
AC05-00OR22725; DMR-1229217; DMR-1157490
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 15; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS