Direct observation of the magnetic ordering process in the ferromagnetic semiconductor GaMnAs via soft X-ray magnetic circular dichroism

Takeda, Yukiharu; Oya, Shinobu*; Pham, N. H.*; Kobayashi, Masaki*; Saito, Yuji; Yamagami, Hiroshi; Tanaka, Masaaki*; Fujimori, Atsushi*

Journal of Applied Physics, 128(21), p.213902_1 - 213902_11, 2020/12

https://doi.org/10.1063/5.0031605

Electronic structure of the high- ferromagnetic semiconductor (Ga,Fe)Sb; X-ray magnetic circular dichroism and resonance photoemission spectroscopy studies

Sakamoto, Shoya*; Tu, N. T.*; Takeda, Yukiharu; Fujimori, Shinichi; Hai, P. N.*; Anh, L. D.*; Wakabayashi, Yuki*; Shibata, Goro*; Horio, Masafumi*; Ikeda, Keisuke*; et al.

Physical Review B, 100(3), p.035204_1 - 035204_8, 2019/07

https://doi.org/10.1103/PhysRevB.100.035204

Electronic structure of URuSi studied by photoelectron spectroscopy (INVITED)

Fujimori, Shinichi; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*

Progress in Nuclear Science and Technology (Internet), 5, p.82 - 85, 2018/11

https://doi.org/10.15669/pnst.5.82

Cation distribution and magnetic properties in ultrathin (NiCo)FeO (x=0-1) layers on Si(111) studied by soft X-ray magnetic circular dichroism

Wakabayashi, Yuki*; Nonaka, Yosuke*; Takeda, Yukiharu; Sakamoto, Shoya*; Ikeda, Keisuke*; Chi, Z.*; Shibata, Goro*; Tanaka, Arata*; Saito, Yuji; Yamagami, Hiroshi; et al.

Physical Review Materials (Internet), 2(10), p.104416_1 - 104416_12, 2018/10

https://doi.org/10.1103/PhysRevMaterials.2.104416

Electronic structures of U (=Al, Ga, and In) studied by photoelectron spectroscopy

Fujimori, Shinichi; Kobata, Masaaki; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*

Physical Review B, 96(11), p.115126_1 - 115126_10, 2017/09

https://doi.org/10.1103/PhysRevB.96.115126

Origin of robust nanoscale ferromagnetism in Fe-doped Ge revealed by angle-resolved photoemission spectroscopy and first-principles calculation

Sakamoto, Shoya*; Wakabayashi, Yuki*; Takeda, Yukiharu; Fujimori, Shinichi; Suzuki, Hakuto*; Ban, Yoshisuke*; Yamagami, Hiroshi; Tanaka, Masaaki*; Oya, Shinobu*; Fujimori, Atsushi*

Physical Review B, 95(7), p.075203_1 - 075203_5, 2017/02

https://doi.org/10.1103/PhysRevB.95.075203

Volume-wise destruction of the antiferromagnetic Mott insulating state through quantum tuning

Frandsen, B. A.*; Liu, L.*; Cheung, S. C.*; Guguchia, Z.*; Khasanov, R.*; Morenzoni, E.*; Munsie, T. J. S.*; Hallas, A. M.*; Wilson, M. N.*; Cai, Y.*; et al.

Nature Communications (Internet), 7, p.12519_1 - 12519_8, 2016/08

https://doi.org/10.1038/ncomms12519

Recent progress of soft X-ray photoelectron spectroscopy studies of uranium compounds

Fujimori, Shinichi; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Yamamoto, Etsuji; Haga, Yoshinori; Onuki, Yoshichika

Journal of Electron Spectroscopy and Related Phenomena, 208, p.105 - 110, 2016/04

https://doi.org/10.1016/j.elspec.2015.08.001

Recent progresses in the soft X-ray photoelectron spectroscopy (PES) studies ( 100 eV) for uranium compounds are briefly reviewed. The soft X-ray PES has enhanced sensitivities for the bulk U 5f electronic structure, which is essential to understand the unique physical properties of uranium compounds. In particular, the recent remarkable improvement in energy resolutions from an order of 1 eV to 100 meV made it possible to observe fine structures in Uf density of states. Furthermore, soft X-ray ARPES becomes available due to the increase of photon flux at beamlines in third generation synchrotron radiation facilities. The technique made it possible to observe bulk band structures and Fermi surfaces of uranium compounds and therefore, the results can be directly compared with theoretical models such as band-structure calculations. The core-level spectra of uranium compounds show a systematic behavior depending on their electronic structures, suggesting that they can be utilized to determine basic physical parameters such as the U 5f-ligand hybridizations or Coulomb interaction between U 5f electrons. It is shown that soft X-ray PES provides unique opportunities to understand the electronic structures of uranium compounds.

Magnetization process of the -type ferromagnetic semiconductor (In,Fe)As:Be studied by X-ray magnetic circular dichroism

Sakamoto, Shoya*; Anh, L. D.*; Hai, P. N.*; Shibata, Goro*; Takeda, Yukiharu; Kobayashi, Masaki*; Takahashi, Yukio*; Koide, Tsuneharu*; Tanaka, Masaaki*; Fujimori, Atsushi*

Physical Review B, 93(3), p.035203_1 - 035203_6, 2016/01

AA2016-0502.pdf:1.1MB

https://doi.org/10.1103/PhysRevB.93.035203

Electronic structures of ferromagnetic superconductors UGe and UCoGe studied by angle-resolved photoelectron spectroscopy

Fujimori, Shinichi; Okochi, Takuo*; kawasaki, Ikuto*; Yasui, Akira*; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; et al.

Physical Review B, 91(17), p.174503_1 - 174503_9, 2015/05

https://doi.org/10.1103/PhysRevB.91.174503

The electronic structures of the ferromagnetic superconductors UGe and UCoGe in the paramagnetic phase were studied by angle-resolved photoelectron spectroscopy using soft X-rays ( = 400-500 eV). The quasi-particle bands with large contributions from U 5 states were observed in the vicinity of EF, suggesting that the U 5 electrons of these compounds have an itinerant character. Their overall band structures were explained by the band-structure calculations treating all the U 5 electrons as being itinerant. Meanwhile, the states in the vicinity of EF show considerable deviations from the results of band-structure calculations, suggesting that the shapes of Fermi surface of these compounds are qualitatively different from the calculations, possibly caused by electron correlation effect in the complicated band structures of the low-symmetry crystals. Strong hybridization between U 5 and states in UCoGe were found by the 2p-3d resonant photoemission experiment, suggesting that states have finite contributions to the magnetic, transport, and superconducting properties.