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Okazaki Group

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.

Fermi-surface map and superconducting gap of the Kagome superconductor Cs(Va,Ta)3Sb5(Tc = 5.2 K)
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