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.

• Publications
• Research Highlights