Dynamical screening effects in pump-probe Hard X-ray Photoelectron Spectroscopy

• Project/Area Number: 15K13526
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Chainani Ashish 国立研究開発法人理化学研究所, 放射光科学総合研究センター, 専任研究員 (80425636)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2016: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2015: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
• Keywords: time-resolved / pump-probe / HAXPES / Time-resolved / Pump-probe

Outline of Final Research Achievements

We have carried out Time-resolved hard X-ray photoelectron spectroscopy (trHAXPES) using microfocused X-ray free-electron laser (XFEL, hnu =8 keV) pulses as a probe and infrared laser pulses (hnu = 1:55 eV) as a pump to determine space-charge effects and separate out intrinsic charge-carrier recombination dynamics in La:SrTiO3. We have used a combination of experiments and numerical N-body simulations for developing a simple approach to characterize and decrease XFEL-induced vacuum space-charge effects. We then show that, using an analytical mean-field model, vacuum space-charge effects can be compensated by pump laser-induced photoholes at high excitation densities. This provides us a method to separate vacuum space-charge effects from the intrinsic charge-carrier recombination dynamics in the time domain. Our trHAXPES results thus open a route to studies of intrinsic charge-carrier dynamics on picosecond time scales with lateral spatial resolution on the micrometer scale.

Research Products

• [Journal Article] Hard x-ray photoelectron spectroscopy experiment at SACLA ~ towards femtosecond time-resolved measurement (2016)
  • Author(s): M. Oura, L.-P. Oloff. K Rossnagel, A. Chainani and M. Matsunami
  • Journal Title: Journal of Japanese Society for Synchrotron Radiation Research Volume: 29
  • Peer Reviewed
• [Journal Article] Time-resolved HAXPES using a microfocused XFEL beam: From vacuum space-charge effects to intrinsic charge-carrier recombination dynamics (2016)
  • Author(s): L.-P. Oloff, A. Chainani, M. Matsunami, K. Takahashi, T. Togashi, H. Osawa, K. Hanff, A. Quer, R. Matsushita, R. Shiraishi, M. Nagashima, A. Kimura, K. Matsuishi, M. Yabashi, Y. Tanaka, G. Rossi, T. Ishikawa, K. Rossnagel and M. Oura
  • Journal Title: Scientific Reports Volume: 6 Issue: 1
  • DOI: 10.1038/srep35087
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Electronic structure evolution across the Peierls metal-insulator transition in a correlated ferromagnet (2015)
  • Author(s): P. A. Bhobe, A. Kumar, M. Taguchi, R. Eguchi, M. Matsunami, Y. Takatay, A. K. Nandy, P. Mahadevan, D. D. Sarma, A. Neroni, E. Saioglu, M. Lezaic, M. Oura, Y. Senba, H. Ohashi, K. Ishizaka, M. Okawa, S. Shin, K. Tamasaku, Y. Kohmura, M. Yabashi, T. Ishikawa, K. Hasegawa, M. Isobe, Y. Ueda, and A. Chainani
  • Journal Title: Physical Review X Volume: 5 Issue: 4
  • DOI: 10.1103/physrevx.5.041004
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Book] Springer Series in Surface Sciences, Hard X-ray Photoelectron Spectroscopy (HAXPES) (2016)
  • Author(s): L.-P. Oloff, M. Oura, A. Chainani and K Rossnagel
  • Publisher: Springer International
• [Book] Springer Series in Surface Sciences : Hard X-ray Photoelectron Spectroscopy (HAXPES) (2016)
  • Author(s): L.-P. Oloff, M. Oura, A. Chainani and K Rossnagel
  • Publisher: Springer