Ayumi Moriya
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Ayumi Moriya has a total of 23 co-authors. Here are the top co-authors by number of shared publications:
- Kosuke Nakayama
Tohoku University
3 shared publications Atsuya Tokuyama
Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
2 shared publications- Hiroshi Kumigashira
Tohoku University
2 shared publications - Kouji Segawa
Kyoto Sangyo University
2 shared publications - Seigo Souma
Tohoku University
2 shared publications - Takafumi Sato
Tohoku University
2 shared publications
Latest Publications
- 5 June 2024
- Published by Springer Nature in Nature
- Vol. 631 (8019) , 54-59
Observation of edge states derived from topological helix chains
Introducing the concept of topology has revolutionized materials classification, leading to the discovery of topological insulators and Dirac–Weyl semimetals1,2,3. One of the most fundamental theories underpinning topological materials is the Su–Schrieffer–Heeger (SSH) model4,5, which was developed in 1979—decades before the recognition of topological insulators—to describe conducting polymers. Distinct from the vast majority of known topological insulators with two and three dimensions1,2,3, the SSH model predicts a one-dimensional analogue of topological insulators, which hosts topological bound states at the endpoints of a chain4,5,6,7,8. To establish this unique and pivotal state, it is crucial to identify the low-energy excitations stemming from bound states, but this has remained unknown in solids because of the absence of suitable platforms. Here we report unusual electronic states that support the emergent bound states in elemental tellurium, the single helix of which was recently proposed to realize an extended version of the SSH chain9,10. Using spin- and angle-resolved photoemission spectroscopy with a micro-focused beam, we have shown spin-polarized in-gap states confined to the edges of the (0001) surface. Our density functional theory calculations indicate that these states are attributed to the interacting bound states originating from the one-dimensional array of SSH tellurium chains. Helices in solids offer a promising experimental platform for investigating exotic properties associated with the SSH chain and exploring topological phases through dimensionality control.
- 5 June 2024
- Published by Springer Nature in Nature
- Vol. 631 (8019) , 54-59
Observation of edge states derived from topological helix chains
Introducing the concept of topology has revolutionized materials classification, leading to the discovery of topological insulators and Dirac–Weyl semimetals1,2,3. One of the most fundamental theories underpinning topological materials is the Su–Schrieffer–Heeger (SSH) model4,5, which was developed in 1979—decades before the recognition of topological insulators—to describe conducting polymers. Distinct from the vast majority of known topological insulators with two and three dimensions1,2,3, the SSH model predicts a one-dimensional analogue of topological insulators, which hosts topological bound states at the endpoints of a chain4,5,6,7,8. To establish this unique and pivotal state, it is crucial to identify the low-energy excitations stemming from bound states, but this has remained unknown in solids because of the absence of suitable platforms. Here we report unusual electronic states that support the emergent bound states in elemental tellurium, the single helix of which was recently proposed to realize an extended version of the SSH chain9,10. Using spin- and angle-resolved photoemission spectroscopy with a micro-focused beam, we have shown spin-polarized in-gap states confined to the edges of the (0001) surface. Our density functional theory calculations indicate that these states are attributed to the interacting bound states originating from the one-dimensional array of SSH tellurium chains. Helices in solids offer a promising experimental platform for investigating exotic properties associated with the SSH chain and exploring topological phases through dimensionality control.
- Open Access
- 6 June 2023
- Published by American Physical Society (APS) in Physical Review Research
- Vol. 5 (2) , 023152
Visualizing crystal twin boundaries of bismuth by high-spatial-resolution ARPES
We have performed micro-/nanofocused angle-resolved photoemission spectroscopy (ARPES) on cleaved single-crystal surfaces of bismuth to clarify the spatially resolved electronic states. While the dominant area of the cleaved surface was found to display the well-known Rashba-spin-split surface state with the (111)-surface origin, the steplike region with a typical width of shows distinctly different band structure and fermiology originating from the hard-to-cleave (100) surface. This unexpected mixture of the (100)-derived electronic states in a tiny area of the cleaved (111) surface is attributed to the crystal planes separated by a twin boundary, as supported by laser microscopy and electron backscatter diffraction measurements. The present study paves a pathway toward investigating electronic states associated with inhomogeneities and coexisting phases of hard-to-cleave crystal planes and complex materials by spatially resolved ARPES, making this technique a powerful method to investigate the interplay between local electronic states and crystal structures when combined with structural characterization techniques.- 6 June 2023
- Published by American Physical Society (APS) in Physical Review Research
- Vol. 5 (2) , 023152
Open AccessVisualizing crystal twin boundaries of bismuth by high-spatial-resolution ARPES
We have performed micro-/nanofocused angle-resolved photoemission spectroscopy (ARPES) on cleaved single-crystal surfaces of bismuth to clarify the spatially resolved electronic states. While the dominant area of the cleaved surface was found to display the well-known Rashba-spin-split surface state with the (111)-surface origin, the steplike region with a typical width of shows distinctly different band structure and fermiology originating from the hard-to-cleave (100) surface. This unexpected mixture of the (100)-derived electronic states in a tiny area of the cleaved (111) surface is attributed to the crystal planes separated by a twin boundary, as supported by laser microscopy and electron backscatter diffraction measurements. The present study paves a pathway toward investigating electronic states associated with inhomogeneities and coexisting phases of hard-to-cleave crystal planes and complex materials by spatially resolved ARPES, making this technique a powerful method to investigate the interplay between local electronic states and crystal structures when combined with structural characterization techniques. - 1 February 2023
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 94 (2) , 023904
Development of Ar gas cluster ion beam system for surface preparation in angle-resolved photoemission spectroscopy
Gas cluster ion beam (GCIB) sputtering has a high potential for obtaining clean and flat surfaces on materials without causing structural or compositional damage. We have developed an Ar cluster GCIB system for surface preparation in angle-resolved photoemission spectroscopy (ARPES). The constructed GCIB system is compatible with ultrahigh vacuum and achieves a beam current of 10 µA. We examined the usefulness of our GCIB system for high surface-sensitive ARPES measurements by applying it to several representative materials, e.g., Sb, GaAs, and Te. The results show that the constructed GCIB system is very useful for preparing a clean flat surface on crystals, widening opportunities for precise ARPES measurements for materials whose crystal surfaces or orientations are hardly obtained by a simple cleaving method.
- 1 February 2023
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 94 (2) , 023904
Development of Ar gas cluster ion beam system for surface preparation in angle-resolved photoemission spectroscopy
Gas cluster ion beam (GCIB) sputtering has a high potential for obtaining clean and flat surfaces on materials without causing structural or compositional damage. We have developed an Ar cluster GCIB system for surface preparation in angle-resolved photoemission spectroscopy (ARPES). The constructed GCIB system is compatible with ultrahigh vacuum and achieves a beam current of 10 µA. We examined the usefulness of our GCIB system for high surface-sensitive ARPES measurements by applying it to several representative materials, e.g., Sb, GaAs, and Te. The results show that the constructed GCIB system is very useful for preparing a clean flat surface on crystals, widening opportunities for precise ARPES measurements for materials whose crystal surfaces or orientations are hardly obtained by a simple cleaving method.