Tetsuya Aruga

Kyoto University

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Kyoto University

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The University of Tokyo

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Tetsuya Aruga has a total of 151 co-authors. Here are the top co-authors by number of shared publications:

Hiroshi Okuyama
Kyoto University
77 shared publications
Shinichiro Hatta
Kyoto University
55 shared publications
M. Nishijima
Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
19 shared publications
Noriaki Takagi
Kyoto University
16 shared publications
Akitoshi Shiotari
Department of Physical Chemistry, Fritz-Haber Institute of the Max-Planck Society 2 , Faradayweg 4-6, 14195 Berlin
14 shared publications
Yoshiyuki Ohtsubo
National Institutes for Quantum Science and Technology, Sendai, Japan
11 shared publications

Latest Publications

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- 26 May 2025
- Published by Elsevier in Surface Science
Relativistic effects at surfaces and interfaces
by Tetsuya Aruga
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- 26 May 2025
- Published by Elsevier in Surface Science
Relativistic effects at surfaces and interfaces
by Tetsuya Aruga
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- 14 November 2024
- Published by American Chemical Society (ACS) in Crystal Growth & Design
Twin-Free Growth of Ultrathin Bi₂Te₃ Films on CaF₂(111)/Si(111)
by Shinichiro Hatta, Shimpei Higaki, Hiroshi Okuyama, Tetsuya Aruga
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- 14 November 2024
- Published by American Chemical Society (ACS) in Crystal Growth & Design
Twin-Free Growth of Ultrathin Bi₂Te₃ Films on CaF₂(111)/Si(111)
by Shinichiro Hatta, Shimpei Higaki, Hiroshi Okuyama, Tetsuya Aruga
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Cited by 6
- 10 June 2024
- Published by American Physical Society (APS) in Physical Review B
Tunneling electron induced luminescence from indium films on Si(111)
by Kenta Kuroishi, Hiroshi Okuyama, Shinichiro Hatta, Tetsuya Aruga
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- 10 June 2024
- Published by American Physical Society (APS) in Physical Review B
Tunneling electron induced luminescence from indium films on Si(111)
by Kenta Kuroishi, Hiroshi Okuyama, Shinichiro Hatta, Tetsuya Aruga
Cited by 6
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Cited by 5
- 31 July 2023
- Published by American Physical Society (APS) in Physical Review B
Moiré superlattice and two-dimensional free-electron-like states of indium triple-layer structure on Si(111)
by Shinichiro Hatta, Kenta Kuroishi, Keisuke Yukawa, Tomoka Murata, Hiroshi Okuyama, Tetsuya Aruga
We studied the growth of an indium triple-atomic-layer film and the two-dimensional free-electron-like electronic states on Si(111) by low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and angle-resolved photoelectron spectroscopy (ARPES). By depositing In on the In/Si(111)- $\sqrt{7} \times \sqrt{3}$ -rect surface below 100 K, followed by brief postannealing up to 140 K, we successfully obtained well-crystalline films exhibiting sharp superstructure LEED spots. We revealed an $(11 \times 11)$ superlattice of the triple-layer structure, while both LEED and STM showed a $(5.5 \times 5.5)$ pseudoperiodicity. This pseudoperiodicity was attributed to the moiré interference between the Si(111)-( $11 \times 11$ ) lattice ( $a$ = 3.84 Å) and the In $(13 \times 13)$ hexagonal lattice, which has a lattice constant of 3.25 Å, with the ratio very close to 13/11. ARPES measurements unveiled two free-electron-like states with Fermi wave vectors of 1.32 and 1.46 $Å^{- 1}$ . We also observed replica Fermi surfaces, which are associated with the reciprocal lattice vectors of both the $(1 \times 1)$ Si(111) and the In hexagonal layers. This further confirms the hexagonal atomic arrangement of the In triple-layer structure.
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- 31 July 2023
- Published by American Physical Society (APS) in Physical Review B
Moiré superlattice and two-dimensional free-electron-like states of indium triple-layer structure on Si(111)
by Shinichiro Hatta, Kenta Kuroishi, Keisuke Yukawa, Tomoka Murata, Hiroshi Okuyama, Tetsuya Aruga
We studied the growth of an indium triple-atomic-layer film and the two-dimensional free-electron-like electronic states on Si(111) by low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and angle-resolved photoelectron spectroscopy (ARPES). By depositing In on the In/Si(111)- $\sqrt{7} \times \sqrt{3}$ -rect surface below 100 K, followed by brief postannealing up to 140 K, we successfully obtained well-crystalline films exhibiting sharp superstructure LEED spots. We revealed an $(11 \times 11)$ superlattice of the triple-layer structure, while both LEED and STM showed a $(5.5 \times 5.5)$ pseudoperiodicity. This pseudoperiodicity was attributed to the moiré interference between the Si(111)-( $11 \times 11$ ) lattice ( $a$ = 3.84 Å) and the In $(13 \times 13)$ hexagonal lattice, which has a lattice constant of 3.25 Å, with the ratio very close to 13/11. ARPES measurements unveiled two free-electron-like states with Fermi wave vectors of 1.32 and 1.46 $Å^{- 1}$ . We also observed replica Fermi surfaces, which are associated with the reciprocal lattice vectors of both the $(1 \times 1)$ Si(111) and the In hexagonal layers. This further confirms the hexagonal atomic arrangement of the In triple-layer structure.
Cited by 5
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Cited by 7
- 1 March 2022
- Published by American Physical Society (APS) in Physical Review B
Ultrathin (In, Mg) films on Si(111): A nearly freestanding double-layer metal
by Shigemi Terakawa, Shinichiro Hatta, Hiroshi Okuyama, Tetsuya Aruga
We report on the formation of triple-atomic-layer metal films on Si(111) by deposition of Mg onto In double-layer films. The deposited Mg atoms are intercalated between the In layers and Si substrate and form a buffer layer with $(\sqrt{3} \times \sqrt{3})$ periodicity on an unreconstructed Si(111) surface. Two metal layers with nearly hexagonal close-packed arrangement are stacked in an ABC sequence on the buffer layer. The (In, Mg) triple-layer phase shows free-electron-like electronic structure with circular Fermi surface. Unlike the single Fermi circle of the In double layers, the Fermi surface of the (In, Mg) triple layers is composed of two circles with different radii. The larger and smaller Fermi circles are found to come from bonding and antibonding states between the top and middle layers of the three layers. The bottom layer acts as a buffer layer to saturate the Si dangling bonds and realize a nearly freestanding double-layer metal.
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- 1 March 2022
- Published by American Physical Society (APS) in Physical Review B
Ultrathin (In, Mg) films on Si(111): A nearly freestanding double-layer metal
by Shigemi Terakawa, Shinichiro Hatta, Hiroshi Okuyama, Tetsuya Aruga
We report on the formation of triple-atomic-layer metal films on Si(111) by deposition of Mg onto In double-layer films. The deposited Mg atoms are intercalated between the In layers and Si substrate and form a buffer layer with $(\sqrt{3} \times \sqrt{3})$ periodicity on an unreconstructed Si(111) surface. Two metal layers with nearly hexagonal close-packed arrangement are stacked in an ABC sequence on the buffer layer. The (In, Mg) triple-layer phase shows free-electron-like electronic structure with circular Fermi surface. Unlike the single Fermi circle of the In double layers, the Fermi surface of the (In, Mg) triple layers is composed of two circles with different radii. The larger and smaller Fermi circles are found to come from bonding and antibonding states between the top and middle layers of the three layers. The bottom layer acts as a buffer layer to saturate the Si dangling bonds and realize a nearly freestanding double-layer metal.
Cited by 7
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Cited by 14
- 8 July 2021
- Published by Royal Society of Chemistry (RSC) in Physical Chemistry Chemical Physics
A flat-lying dimer as a key intermediate in NO reduction on Cu(100)
by Kenta Kuroishi, Muhammad Rifqi Al Fauzan, Thanh Ngoc Pham, Yuelin Wang, Yuji Hamamoto, Kouji Inagaki, Akitoshi Shiotari, Hiroshi Okuyama, Shinichiro Hatta, Tetsuya Aruga, et al.
The reaction of nitric oxide (NO) on Cu(100) is studied by scanning tunneling microscopy, electron energy loss spectroscopy and density functional theory calculations. The NO molecules adsorb mainly as monomers at 64 K, and react and dissociate to yield oxygen atoms on the surface at ∼70 K. The temperature required for the dissociation is significantly low for Cu(100), compared to those for Cu(111) and Cu(110). The minimum energy pathway of the reaction is via (NO)₂ formation, which converts into a flat-lying ONNO and then dissociates into N₂O and O with a considerably low activation energy. We propose that the formation of (NO)₂ and flat-lying ONNO is the key to the exceptionally high reactivity of NO on Cu(100).
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- 8 July 2021
- Published by Royal Society of Chemistry (RSC) in Physical Chemistry Chemical Physics
A flat-lying dimer as a key intermediate in NO reduction on Cu(100)
by Kenta Kuroishi, Muhammad Rifqi Al Fauzan, Thanh Ngoc Pham, Yuelin Wang, Yuji Hamamoto, Kouji Inagaki, Akitoshi Shiotari, Hiroshi Okuyama, Shinichiro Hatta, Tetsuya Aruga, et al.
The reaction of nitric oxide (NO) on Cu(100) is studied by scanning tunneling microscopy, electron energy loss spectroscopy and density functional theory calculations. The NO molecules adsorb mainly as monomers at 64 K, and react and dissociate to yield oxygen atoms on the surface at ∼70 K. The temperature required for the dissociation is significantly low for Cu(100), compared to those for Cu(111) and Cu(110). The minimum energy pathway of the reaction is via (NO)₂ formation, which converts into a flat-lying ONNO and then dissociates into N₂O and O with a considerably low activation energy. We propose that the formation of (NO)₂ and flat-lying ONNO is the key to the exceptionally high reactivity of NO on Cu(100).
Cited by 14
Open Access
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Cited by 3
- 11 March 2021
- Published by Springer Nature in Scientific Reports
Metallic conduction through van der Waals interfaces in ultrathin $\hbox{Bi}_2\hbox{Te}_3$ films
by Shinichiro Hatta, Ko Obayashi, Hiroshi Okuyama, Tetsuya Aruga
While the van der Waals (vdW) interface in layered materials hinders the transport of charge carriers in the vertical direction, it serves a good horizontal conduction path. We have investigated electrical conduction of few quintuple-layer (QL) $$\hbox {Bi}_2\hbox {Te}_3$$ ${Bi}_{2} {Te}_{3}$ films by in situ four-point probe conductivity measurement. The impact of the vdW (Te–Te) interface appeared as a large conductivity increase with increasing thickness from 1 to 2 QL. Angle-resolved photoelectron spectroscopy and first-principles calculations reveal the confinement of bulk-like conduction band (CB) state into the vdW interface. Our analysis based on the Boltzmann equation showed that the conduction of the CB has a long mean free path compared to the surface-state conduction. This is mainly attributed to the spatial separation of the CB electrons and the donor defects located at the Bi sites.
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- 11 March 2021
- Published by Springer Nature in Scientific Reports
Open Access
Metallic conduction through van der Waals interfaces in ultrathin $\hbox{Bi}_2\hbox{Te}_3$ films
by Shinichiro Hatta, Ko Obayashi, Hiroshi Okuyama, Tetsuya Aruga
While the van der Waals (vdW) interface in layered materials hinders the transport of charge carriers in the vertical direction, it serves a good horizontal conduction path. We have investigated electrical conduction of few quintuple-layer (QL) $$\hbox {Bi}_2\hbox {Te}_3$$ ${Bi}_{2} {Te}_{3}$ films by in situ four-point probe conductivity measurement. The impact of the vdW (Te–Te) interface appeared as a large conductivity increase with increasing thickness from 1 to 2 QL. Angle-resolved photoelectron spectroscopy and first-principles calculations reveal the confinement of bulk-like conduction band (CB) state into the vdW interface. Our analysis based on the Boltzmann equation showed that the conduction of the CB has a long mean free path compared to the surface-state conduction. This is mainly attributed to the spatial separation of the CB electrons and the donor defects located at the Bi sites.
Cited by 3
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Cited by 9
- 16 September 2019
- Published by American Physical Society (APS) in Physical Review B
Structure and phase transition of a uniaxially incommensurate In monolayer on Si(111)
by Shigemi Terakawa, Shinichiro Hatta, Hiroshi Okuyama, Tetsuya Aruga
We have studied the atomic structure and phase transition of a dense metallic monolayer of In on Si(111). Although the monolayer phase was previously considered to have a $(\sqrt{7} \times \sqrt{3})$ periodicity, low-energy electron diffraction and scanning tunneling microscopy observations have revealed that the phase has an incommensurate structure with the In overlayer uniaxially contracted by 2% from $(\sqrt{7} \times \sqrt{3})$ . The uniaxially contracted structure was found to be more stable than the commensurate $(\sqrt{7} \times \sqrt{3})$ structure by first-principles calculations. We also observed a phase transition to a $(\sqrt{7} \times \sqrt{7})$ phase at 250–210 K upon cooling. Angle-resolved photoelectron spectroscopy and macroscopic four-point-probe conductivity measurements demonstrated that the transition induces the disappearance of metallic surface states and a sharp drop in sheet conductivity, respectively. These results indicate an electronic metal-insulator transition.
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- 16 September 2019
- Published by American Physical Society (APS) in Physical Review B
Structure and phase transition of a uniaxially incommensurate In monolayer on Si(111)
by Shigemi Terakawa, Shinichiro Hatta, Hiroshi Okuyama, Tetsuya Aruga
We have studied the atomic structure and phase transition of a dense metallic monolayer of In on Si(111). Although the monolayer phase was previously considered to have a $(\sqrt{7} \times \sqrt{3})$ periodicity, low-energy electron diffraction and scanning tunneling microscopy observations have revealed that the phase has an incommensurate structure with the In overlayer uniaxially contracted by 2% from $(\sqrt{7} \times \sqrt{3})$ . The uniaxially contracted structure was found to be more stable than the commensurate $(\sqrt{7} \times \sqrt{3})$ structure by first-principles calculations. We also observed a phase transition to a $(\sqrt{7} \times \sqrt{7})$ phase at 250–210 K upon cooling. Angle-resolved photoelectron spectroscopy and macroscopic four-point-probe conductivity measurements demonstrated that the transition induces the disappearance of metallic surface states and a sharp drop in sheet conductivity, respectively. These results indicate an electronic metal-insulator transition.
Cited by 9
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Cited by 5
- 1 December 2018
- Published by Elsevier in Surface Science
Effect of adsorbates on single-molecule junction conductance
by H. Okuyama, H. So, S. Hatta, T. Frederiksen, T. Aruga
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- 1 December 2018
- Published by Elsevier in Surface Science
Effect of adsorbates on single-molecule junction conductance
by H. Okuyama, H. So, S. Hatta, T. Frederiksen, T. Aruga
Cited by 5
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Cited by 10
- 16 August 2018
- Published by IOP Publishing in Journal of Physics: Condensed Matter
Identification of single-layer metallic structure of indium on Si(1 1 1)
by Shigemi Terakawa, Shinichiro Hatta, Hiroshi Okuyama, Tetsuya Aruga
We have studied the In/Si(1 1 1) ( )-hex and striped phases by low-energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). The two phases are formed by different processes, and hence the different names have been used conventionally. We, however, found that LEED I – curves of the two phases agree with each other, indicating that they have an identical atomic structure. Our ARPES measurement revealed that the ( )-hex phase has metallic surface states. The observed Fermi surface was found to be very similar to the theoretical one calculated for an indium single-layer model.
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- 16 August 2018
- Published by IOP Publishing in Journal of Physics: Condensed Matter
Identification of single-layer metallic structure of indium on Si(1 1 1)
by Shigemi Terakawa, Shinichiro Hatta, Hiroshi Okuyama, Tetsuya Aruga
We have studied the In/Si(1 1 1) ( )-hex and striped phases by low-energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). The two phases are formed by different processes, and hence the different names have been used conventionally. We, however, found that LEED I – curves of the two phases agree with each other, indicating that they have an identical atomic structure. Our ARPES measurement revealed that the ( )-hex phase has metallic surface states. The observed Fermi surface was found to be very similar to the theoretical one calculated for an indium single-layer model.
Cited by 10

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