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Okazaki Group

member
Associate Professor OKAZAKI, Kozo
Research Associate SUZUKI, Takeshi

Research Subjects

  • Mechanisms of unconventional superconductivities investigated by ultralow-temperature and ultrahigh-resolution laser ARPESr
  • Mechanisms of photo-induced phase transitions investigated by HHG laser time-resolved ARPES
  • Developments of high-resolution/time-resolved ARPES systems using advanced lasers

Angle-resolved photoemission spectroscopy is a very powerful experimental technique that can directly observe a dispersion relation between momentum and energy (band structure) of the electrons in solid-state materials. In our group, we are aiming for understanding the mechanisms of unconventional superconductivity by direct observations of the electronic structures and superconducting-gap structures of unconventional superconductors by laser-based angle-resolved photoemission system with a world-record performance that achieves the maximum energy resolution of 70 μeV and lowest cooling temperature of 1K. In addition, by time-resolved photoemission spectroscopy utilizing a femtosecond laser as pumping light and its high harmonic as probing light, we can observe ultrafast transient properties of the band structure in a non-equilibrium state. We are aiming for understanding the mechanisms of photo-induced phase transitions and control of physical properties of materials by light by using time-resolved photoemission spectroscopy utilizing high harmonic laser as probing light. We are also developing and improving photoemission systems that utilizes advanced lasers in collaboration with the laser development groups.

fig1
Fermi-surface map and superconducting gap of the Kagome superconductor Cs(Va,Ta)3Sb5(Tc = 5.2 K)
fig2
Photo-induced insulator-to-metal transition in an excitonic insulator Ta2NiSe5 observed by HHG laser TRPES. a, b. Spectra before and after pump, respectively.

Publications and Research Highlights