# Angle-Resolved Photoemission Spectroscopy - Explore the Science & Experts | ideXlab

## Angle-Resolved Photoemission Spectroscopy

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### Takafumi Sato – One of the best experts on this subject based on the ideXlab platform.

• ##### Superstructure-dependent electronic states in CaAlSi superconductors studied by Angle-ResolvedPhotoemissionSpectroscopy
Physical Review B, 2015
Co-Authors: Takafumi Sato, Katsuaki Sugawara, Seigo Souma, Jun Akimitsu, Y. X. Xiao, Kosuke Nakayama, S. Kuroiwa, Takashi Takahashi
Abstract:

We have performed high-resolution Angle-Resolved Photoemission Spectroscopy on layered polymorph series of $1H\ensuremath{-}, 5H\ensuremath{-}$, and $6H\ensuremath{-}\mathrm{CaAlSi}$, which exhibit superconductivity below 6.5, 5.7, and 7.7 K, respectively. While the overall band structure in the valence-band region is similar among these compounds, the volume of the Fermi surface at the $M$ point and the magnitude of the superconducting gap are markedly different from each other. Implications of such variation in the electronic structure due to the superstructure along the $c$ axis are discussed in relation to the physical properties of CaAlSi.

• ##### Fe-based superconductors: an Angle-ResolvedPhotoemissionSpectroscopy perspective
Reports on Progress in Physics, 2011
Co-Authors: Pierre Richard, Takafumi Sato, Takashi Takahashi, K. Nakayama, Hong Ding
Abstract:

Angle-Resolved Photoemission Spectroscopy allows direct visualization and experimental determination of the electronic structure of crystals in the momentum space, including the precise characterization of the Fermi surface and the superconducting order parameter. It is thus particularly suited for investigating multi-band systems such as the Fe-based superconductors. In this review, we cover several aspects of these recently discovered materials that have been addressed by this technique, with a special emphasis on their superconducting gap and their Fermi surface topology. We provide sufficient experimental evidence to support the reliability and the consistency of the Angle-Resolved Photoemission Spectroscopy measurements over a wide range of material compositions.

• ##### Angle-ResolvedPhotoemissionSpectroscopy of Graphene, Graphite, and Related Compounds
Comprehensive Semiconductor Science and Technology, 2011
Co-Authors: Takafumi Sato, Takashi Takahashi
Abstract:

High-resolution Angle-Resolved Photoemission Spectroscopy (ARPES) studies on carbon-based materials, such as graphene, graphite, and graphite intercalation compounds (GICs), are presented. We briefly review the basic principle of ARPES technique as well as the recent development of experimental apparatus, and then focus on the electronic structure in the vicinity of the Fermi level responsible for novel physical properties. We discuss the energy band structure and the Fermi surface of graphene and graphite in terms of the many-body interaction, the edge-localized states, and the Dirac-fermion-like behavior. We also explain the first direct ARPES observation of the interlayer band and the superconducting gap in a high-Tc GIC, C6Ca.

### Takashi Takahashi – One of the best experts on this subject based on the ideXlab platform.

• ##### Superstructure-dependent electronic states in CaAlSi superconductors studied by Angle-ResolvedPhotoemissionSpectroscopy
Physical Review B, 2015
Co-Authors: Takafumi Sato, Katsuaki Sugawara, Seigo Souma, Jun Akimitsu, Y. X. Xiao, Kosuke Nakayama, S. Kuroiwa, Takashi Takahashi
Abstract:

We have performed high-resolution Angle-Resolved Photoemission Spectroscopy on layered polymorph series of $1H\ensuremath{-}, 5H\ensuremath{-}$, and $6H\ensuremath{-}\mathrm{CaAlSi}$, which exhibit superconductivity below 6.5, 5.7, and 7.7 K, respectively. While the overall band structure in the valence-band region is similar among these compounds, the volume of the Fermi surface at the $M$ point and the magnitude of the superconducting gap are markedly different from each other. Implications of such variation in the electronic structure due to the superstructure along the $c$ axis are discussed in relation to the physical properties of CaAlSi.

• ##### Fe-based superconductors: an Angle-ResolvedPhotoemissionSpectroscopy perspective
Reports on Progress in Physics, 2011
Co-Authors: Pierre Richard, Takafumi Sato, Takashi Takahashi, K. Nakayama, Hong Ding
Abstract:

Angle-Resolved Photoemission Spectroscopy allows direct visualization and experimental determination of the electronic structure of crystals in the momentum space, including the precise characterization of the Fermi surface and the superconducting order parameter. It is thus particularly suited for investigating multi-band systems such as the Fe-based superconductors. In this review, we cover several aspects of these recently discovered materials that have been addressed by this technique, with a special emphasis on their superconducting gap and their Fermi surface topology. We provide sufficient experimental evidence to support the reliability and the consistency of the Angle-Resolved Photoemission Spectroscopy measurements over a wide range of material compositions.

• ##### Angle-ResolvedPhotoemissionSpectroscopy of Graphene, Graphite, and Related Compounds
Comprehensive Semiconductor Science and Technology, 2011
Co-Authors: Takafumi Sato, Takashi Takahashi
Abstract:

High-resolution Angle-Resolved Photoemission Spectroscopy (ARPES) studies on carbon-based materials, such as graphene, graphite, and graphite intercalation compounds (GICs), are presented. We briefly review the basic principle of ARPES technique as well as the recent development of experimental apparatus, and then focus on the electronic structure in the vicinity of the Fermi level responsible for novel physical properties. We discuss the energy band structure and the Fermi surface of graphene and graphite in terms of the many-body interaction, the edge-localized states, and the Dirac-fermion-like behavior. We also explain the first direct ARPES observation of the interlayer band and the superconducting gap in a high-Tc GIC, C6Ca.

### Seigo Souma – One of the best experts on this subject based on the ideXlab platform.

• ##### Superstructure-dependent electronic states in CaAlSi superconductors studied by Angle-ResolvedPhotoemissionSpectroscopy
Physical Review B, 2015
Co-Authors: Takafumi Sato, Katsuaki Sugawara, Seigo Souma, Jun Akimitsu, Y. X. Xiao, Kosuke Nakayama, S. Kuroiwa, Takashi Takahashi
Abstract:

We have performed high-resolution Angle-Resolved Photoemission Spectroscopy on layered polymorph series of $1H\ensuremath{-}, 5H\ensuremath{-}$, and $6H\ensuremath{-}\mathrm{CaAlSi}$, which exhibit superconductivity below 6.5, 5.7, and 7.7 K, respectively. While the overall band structure in the valence-band region is similar among these compounds, the volume of the Fermi surface at the $M$ point and the magnitude of the superconducting gap are markedly different from each other. Implications of such variation in the electronic structure due to the superstructure along the $c$ axis are discussed in relation to the physical properties of CaAlSi.

• ##### Electronic structure of LaAgSb2 and CeAgSb2 studied by high-resolution Angle-ResolvedPhotoemissionSpectroscopy
Journal of Magnetism and Magnetic Materials, 2007
Co-Authors: Toshiyuki Arakane, Takafumi Sato, Seigo Souma, Takashi Takahashi, Y. Watanabe, Yoshihiko Inada
Abstract:

Abstract We performed high-resolution Angle-Resolved Photoemission Spectroscopy (ARPES) on quasi-two-dimensional rare-earth intermetallic compounds LaAgSb 2 and CeAgSb 2 . In CeAgSb 2 , we found highly dispersive bands in the vicinity of the Fermi level, showing a hole-like dispersion centered at the Γ(Z) point in the Brillouin zone. These bands produce small hole pockets at the zone center, in good agreement with the band calculation of LaAgSb 2 .

• ##### Anomalous electronic states in graphite studied by Angle-ResolvedPhotoemissionSpectroscopy
Science and Technology of Advanced Materials, 2006
Co-Authors: Katsuaki Sugawara, Takafumi Sato, Seigo Souma, Takashi Takahashi, Hiroshi Suematsu
Abstract:

We report high-resolution Angle-Resolved Photoemission Spectroscopy (ARPES) on high quality single crystal of graphite (kish grapgraphite) to elucidate the origin of anomalous physical properties of carbon-based materials. We found an almost flat band in the vicinity of the Fermi level around the K(H) point which is not predicted by the bulk band calculation. We discuss the origin of this anomalous structure in relation to the edge-localized state on the step edges of cleaved surface.

### Yoshichika Ōnuki – One of the best experts on this subject based on the ideXlab platform.

• ##### Electronic Structure of Trivalent Compound EuPd3 Studied by Soft X-ray Angle-ResolvedPhotoemissionSpectroscopy
Journal of the Physical Society of Japan, 2020
Co-Authors: Ikuto Kawasaki, M. Kobata, Shin-ichi Fujimori, Yukiharu Takeda, Hiroshi Yamagami, Ai Nakamura, Wataru Iha, Masato Hedo, Takao Nakama, Yoshichika Ōnuki
Abstract:

EuPd3 is a rare Eu-based compound, whose Eu ions are in a trivalent state. The electronic structure of EuPd3 was investigated by Angle-Resolved Photoemission Spectroscopy (ARPES) using soft x rays….

• ##### Itinerant U 5f Nature in Antiferromagnet U(Ru0.97Rh0.03)2Si2: Soft X-ray Angle-ResolvedPhotoemissionSpectroscopy
Journal of the Physical Society of Japan, 2011
Co-Authors: Ikuto Kawasaki, Yoshinori Haga, E. Yamamoto, Shin-ichi Fujimori, Hiroshi Yamagami, Tetsuo Okane, Akira Yasui, Yuji Saitoh, Yoshichika Ōnuki
Abstract:

We have carried out soft X-ray Angle-Resolved Photoemission Spectroscopy experiments on U(Ru 0.97 Rh 0.03 ) 2 Si 2 , which shows antiferromagnetic (AFM) ordering at low temperatures. We have reveal…

• ##### Band structure ofUPd3studied by ultrahigh-resolution Angle-ResolvedPhotoemissionSpectroscopy
Physical Review B, 2002
Co-Authors: Takahiro Ito, Seigo Souma, Hiroshi Kumigashira, Yoshinori Haga, Yoshihumi Tokiwa, T. Takahashi, Yoshichika Ōnuki
Abstract:

We have performed ultrahigh-resolution Angle-Resolved Photoemission Spectroscopy on UPd 3 to study the band structure near the Fermi level (E F ) and the Fermi surface. We found three Fermi surfaces (FS’s): two hole pockets with a dominant Pd 4d character at the Γ (A) point and an electron pocket with a U 6d nature at the K (H) point. These FS’s are qualitatively well reproduced in the band structure calculation based on the localized U-5f-electron model, while remarkable quantitative discrepancies are observed near E F . The U 5f states are located 0.4-1.0 eV below E F and do not contribute to the Fermi surface. These results indicate the strongly localized nature of U 5f electrons in UPd 3 .

### Takahiro Ito – One of the best experts on this subject based on the ideXlab platform.

• ##### Orbital-dependent electron correlation in LiFeAs revealed by Angle-ResolvedPhotoemissionSpectroscopy
Physical Review B, 2016
Co-Authors: Tetsuya Hajiri, Takahiro Ito, Yong Seung Kwon, Masaharu Matsunami, B. H. Min, Kazuhiko Kuroki, S. Kimura
Abstract:

We report on the electronic structure of the 111-type iron pnictide superconductor LiFeAs as a function of temperature using Angle-Resolved Photoemission Spectroscopy. Below approximately 50 K, both the ${d}_{yz}$ hole band at the $Z$ point and the ${d}_{xz/yz}$ electron band at the $A$ point shift to a higher binding energy side. However, at the high-symmetry points $Z,\phantom{\rule{0.16em}{0ex}}A,\phantom{\rule{0.16em}{0ex}}\mathrm{\ensuremath{\Gamma}}$, and $M$, the remaining bands are almost independent of temperature. One of the possible scenarios for these observations is that a strong, three-dimensional orbital-dependent correlation exists in the normal state of LiFeAs in relation to short-range spin fluctuations.

• ##### Band structure ofUPd3studied by ultrahigh-resolution Angle-ResolvedPhotoemissionSpectroscopy
Physical Review B, 2002
Co-Authors: Takahiro Ito, Seigo Souma, Hiroshi Kumigashira, Yoshinori Haga, Yoshihumi Tokiwa, T. Takahashi, Yoshichika Ōnuki
Abstract:

We have performed ultrahigh-resolution Angle-Resolved Photoemission Spectroscopy on UPd 3 to study the band structure near the Fermi level (E F ) and the Fermi surface. We found three Fermi surfaces (FS’s): two hole pockets with a dominant Pd 4d character at the Γ (A) point and an electron pocket with a U 6d nature at the K (H) point. These FS’s are qualitatively well reproduced in the band structure calculation based on the localized U-5f-electron model, while remarkable quantitative discrepancies are observed near E F . The U 5f states are located 0.4-1.0 eV below E F and do not contribute to the Fermi surface. These results indicate the strongly localized nature of U 5f electrons in UPd 3 .

• ##### Electronic structure of black SmS. II. Angle-ResolvedPhotoemissionSpectroscopy
Physical Review B, 2002
Co-Authors: Takahiro Ito, Takashi Takahashi, Hiroshi Kumigashira, Ashish Chainani, Noriaki K. Sato
Abstract:

We have studied the electronic bandband structure of semiconducting black SmS with high-resolution Angle-Resolved Photoemission Spectroscopy (ARPES). The valence band consists of two well-separated groups of bands: almost nondispersive bands near E F and highly dispersive bands at higher binding energy. The former is ascribed to the Sm 2 (4f 6 →4f 5 ) multiplet and the latter to mainly the S 3p states. We found a small but distinct energy dispersion in the Sm 4f-derived bands near E F . This indicates a strong hybridization between the “localized” Sm 4f electrons and the “itinerant” conduction electrons, leading to the “delocalized” Sm 4f states in mixed-valent SmS. We have compared the present ARPES results with a recent periodic Anderson model calculation [C. Lehner et al., Phys. Rev. B 58, 6807 (1998)].