The University of Tokyo · Materials Science
Professor Iwao Matsuda's research lab specializes in the electronic structure and quantum phenomena of low-dimensional materials, with a focus on two-dimensional systems, surface states, and quantum well states. The lab employs advanced spectroscopic techniques—particularly angle-resolved photoemission spectroscopy (ARPES) and scanning probe microscopy—to investigate topological electronic states, atomic-scale electron transport, and symmetry-driven electronic reconstructions at surfaces and interfaces. Key research directions include the emergence of Dirac fermions in novel 2D materials like borophene, the transport properties across atomic steps, and the electronic behavior of confined electrons in epitaxial metal films on semiconductors. The lab also explores the interplay between electronic topology, symmetry breaking, and electron correlation effects in low-dimensional systems.
Figures are computed from collected data and may differ slightly.
2D anisotropic Dirac cones are observed in χ<sub>3</sub> borophene, a monolayer boron sheet, using high-resolution angle-resolved photoemission spectroscopy. The Dirac cones are centered at the X and X' points. The data also reveal that the hybridization between borophene and Ag(111) is very weak, which explains the preservation of the Dirac cones. As χ<sub>3</sub> borophene has been predicated to be a superconductor, the results may stimulate further research interest in the novel physics of bo
We have succeeded in measuring the resistance across a single atomic step through a monatomic-layer metal on a crystal surface, Si(111)(sqrt[3]xsqrt[3])-Ag, using three independent methods, which yielded consistent values of the resistance. Two of the methods were direct measurements with monolithic microscopic four-point probes and four-tip scanning tunneling microscope probes. The third method was the analysis of electron standing waves near step edges, combined with the Landauer formula for 2
In-plane dispersion of the quantum-well states (QWS's) associated with the electron confinement in metastable epitaxial Ag films grown on the $\mathrm{Si}(111)7\ifmmode\times\else\texttimes\fi{}7$ and $\mathrm{Si}(001)2\ifmmode\times\else\texttimes\fi{}1$ surfaces is investigated by angle-resolved photoemission using synchrotron radiation. In contrast to the free-electron-like behavior expected, these QWS's show intriguing dispersions such as (i) a significant enhancement of the in-plane effecti
Our photoemission spectroscopy results clearly demonstrate that symmetry breakdown in atomic arrangement brings about a lift of degeneracy in electronic states, leading to settle a long-standing controversy on a surface superstructure. We provide unambiguous evidences that $\mathrm{Si}(111)\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}\ensuremath{-}\mathrm{Ag}$ has the inequivalent triangle structure (IET), excluding a long-lived honeycomb-chained triangle model. We also give critical experi
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