Title: Imaging Emergent Electronic States in Quantum Materials: Micro- and Nano-ARPES
Speaker: Takafumi Sato，Tohoku University
Time: 2026-05-27 10：00
Venue: Room W105, Physics Building
Abstract:Electronic band structures underpin the physical properties of crystalline solids. Angle resolved photoemission spectroscopy (ARPES), grounded in the external photoelectric effect, has long been the workhorse for mapping these structures in quantum materials ranging from high temperature superconductors to topological insulators. Recent advances — most notably spin and time resolved ARPES — now allow us to probe spin textures and ultrafast electron dynamics. The newest frontier is spatially resolved ARPES, which extends these capabilities to samples and devices that were previously out of reach [1].
In this talk, I will survey the rapid progress of the technique and spotlight several key results:
Hard‑to‑cleave bulk crystals — direct band‑structure determination for bulk crystals with strong 3D bonding [2].
Micron‑sized powders — electronic mapping of quantities too small for conventional ARPES [3].
Domain‑resolved studies — identification of polar, magnetic, and structural domains that govern exotic phenomena, including one‑dimensional edge states in topological chiral crystals [4],intertwined charge order and superconductivity in kagome lattices [5],antiferromagnetic topological insulator [6].near‑room‑temperature ferromagnetism in atomic-layer materials [7].
Origin of multiple skyrmion phases [8].
Finally, I will discuss how next generation synchrotron facilities such as NanoTerasu at Tohoku University campus will integrate spatially resolved ARPES into a broader quantum materials toolkit, enabling routine visualization of hidden electronic states with sub micron precision.
[1] Nat. Rev. Methods Primers 2, 54 (2022)
[2] Phys. Rev. B 109, 115102 (2024)
[3] Nano Lett. 23, 1673 (2023)
[4] Nature 631, 54 (2024)
[5] Phys. Rev. X 12, 011001 (2022)
[6] Nat. Commun. 14, 7396 (2023)
[7] Nat. Commun. 16, 3448 (2025)
[8] Nat. Commun. 17, 3162 (2026)
Bio：Prof. Takafumi Sato is currently a Professor at the Advanced Institute for Materials Research (WPI-AIMR), Tohoku University. He received Bachelor’s and Doctorate’s degrees in Physics from Tohoku University in 1997 and 2002, respectively. After a postdoctoral fellowship with JSPS, he joined the faculty at Tohoku University, where he has served as a Professor in the Department of Physics since 2017. He’s research focuses on the electronic structure of quantum materials, including high-temperature superconductors, topological insulators, and atomic-layer materials, using ultrahigh-resolution angle-resolved photoemission spectroscopy (ARPES). He has made significant contributions to the development of spin-resolved ARPES and spatially-resolved (micro/nano-ARPES) techniques, enabling the discovery of novel electronic states in a wide range of functional materials.
