T. Mizokawa

Waseda University

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Co-Authors

A. Fujimori

The University of Tokyo

196

N. L. Saini

Sapienza University of Rome

104

M. Nohara

Hiroshima University

Kou Takubo

Tokyo Institute of Technology

Daiki Ootsuki

Kyoto University

H. Namatame

Hiroshima University

Masashi Arita

Hiroshima University

M. Taniguchi

Hiroshima University

Hiroki Wadati

University of Hyogo

T. Yoshida

Kyoto University

Cooperative Institutions

The University of Tokyo

382

Tohoku University

151

Japan Science and Technology Agency

141

Osaka University

140

Kyoto University

108

Tokyo University of Science

104

Tokyo Institute of Technology

National Institute for Materials Science

National Institute of Advanced Industrial Science and Technology

Hiroshima University

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Localized and mixed valence state of Ce4fin superconducting and ferromagneticCeO1−xFxBiS…

Physical review. B./Physical review. B (2016)

T. Sugimoto Daiki Ootsuki E. Paris Antonella Iadecola M. Salomé

We have performed Ce $L_3$-edge x-ray absorption spectroscopy (XAS) and Ce $4d$-$4f$ resonant photoemission spectroscopy (PES) on single crystals of CeO$_{1-x}$F$_x$BiS$_2$ for $x=0.0$ and 0.5 in order to investigate the Ce $4f$ electronic states. In the Ce $L_3$-edge XAS, mixed valence of Ce was found in the $x=0.0$ sample and the F-doping suppresses it, which is consistent with the results on polycrystalline samples. As for the resonant PES, we found that the Ce $4f$ electrons in both $x=0.0$ and $0.5$ systems respectively form a flat band at 1.0 eV and 1.4 eV below the Fermi level and there is no contribution to the Fermi surfaces. Interestingly, Ce valence in CeOBiS$_2$ deviates from Ce$^{3+}$ even though Ce $4f$ electrons are localized, indicating the Ce valence is not in a typical valence fluctuation regime. We assume that localized Ce $4f$ in CeOBiS$_2$ is mixed with the unoccupied Bi $6p_z$, which is consistent with the previous local structural study. Based on the analysis of the Ce $L_3$-edge XAS spectra using Anderson's impurity model calculation, we found that the transfer integral becomes smaller increasing the number of Ce $4f$ electrons upon the F substitution for O.

X-ray absorption spectroscopy

Anderson impurity model

Absorption edge

10.1103/physrevb.94.081106

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Citations (17)

Photoemission and Hartree-Fock studies of oxygen-hole ordering in charge-disproportionatedLa1−xSrx

Physical review. B, Condensed matter (1999)

Jobu Matsuno T. Mizokawa A. Fujimori K. Mamiya Y. Takeda

We have studied the ``charge disproportionation'' phenomenon in ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{FeO}}_{3}$ by photoemission spectroscopy and unrestricted Hartree-Fock band-structure calculations. We find a systematic decrease of the spectral intensity near Fermi level ${(E}_{F})$ toward $x=0.67,$ where the charge disproportion is most stabilized. The spectra for $x=0.67$ show the clearest temperature-dependent changes in the vicinity of ${E}_{F}$ across the transition corresponding to the charge ordering of $``{\mathrm{Fe}}^{3+}''$:$``{\mathrm{Fe}}^{5+}''\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2:1.$ The Hartree-Fock calculations indicate that ordering of oxygen holes indeed occurs in the charge disproportionated state.

Charge ordering

10.1103/physrevb.60.4605

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Citations (65)

19pWK-3 Orbital states of t_ eletron systems with Pyrochlore lattice : itinerant or localized

Meeting abstracts of the Physical Society of Japan (2007)

T. Mizokawa

Lattice (music)

Source

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Domain dependent Fermi arcs observed in a striped phase dichalcogenide

arXiv (Cornell University) (2021)

T. Mizokawa A. Barinov V. Kandyba A. Giampietri R. Matsumoto

Angle-resolved photoemission spectromicroscopy on IrTe2 reveals evolution of mesoscopic striped domains across its first order phase transition at about 280 K. The striped texture of the domains is characterized by a herringbone arrangement of the electronic anisotropy axes. Under further cooling down to 47 K, the striped domains evolve into trijunction domains with the electronic anisotropy in three directions. Each domain harbors quasi one-dimensional surface bands forming Fermi arcs with peculiar spin polarization. The Fermi arc corresponds to an edge state of the two-dimensional bulk electronic states truncated at the surface, indicating an interesting interplay between the symmetry breaking and the surface electronic states.

Mesoscopic physics

Pseudogap

10.48550/arxiv.2112.05930

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Spectromicroscopy of electronic phase separation in KxFe2−ySe2 superconductor

Scientific Reports (2014)

M. Bendele Alexei Barinov Boby Joseph Davide Innocenti Antonella Iadecola

Structural phase separation in AxFe2−ySe2 system has been studied by different experimental techniques, however, it should be important to know how the electronic uniformity is influenced, on which length scale the electronic phases coexist and what is their spatial distribution. Here, we have used novel scanning photoelectron microscopy (SPEM) to study the electronic phase separation in KxFe2−ySe2, providing a direct measurement of the topological spatial distribution of the different electronic phases. The SPEM results reveal a peculiar interconnected conducting filamentary phase that is embedded in the insulating texture. The filamentary structure with a particular topological geometry could be important for the high Tc superconductivity in the presence of a phase with a large magnetic moment in AxFe2−ySe2 materials.

Texture (cosmology)

10.1038/srep05592

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Citations (36)

Beyond a cluster-Mott state in the breathing kagome lattice of LiZn2Mo3O8

Physical review. B./Physical review. B (2025)

S. V. Streltsov D. Takegami R. Nakamura P. P. Kovaleva A. I. Poteryaev

10.1103/physrevb.111.085124

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Linear dichroic x-ray absorption response of Ti-Ti dimers along the c axis in Ti2O3 upon Mg substitution

Physical review. B./Physical review. B (2023)

Mario Okawa D. Takegami Denise S. Christovam Miguel Ferreira-Carvalho Chang‐Yang Kuo

Corundum oxide ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$ shows the metal-insulator transition around 400--600 K accompanying the nearest ${\mathrm{Ti}}^{3+}\text{\ensuremath{-}}{\mathrm{Ti}}^{3+}$ bond (${a}_{1g}{a}_{1g}$ singlet state) formation along the $c$ axis. In order to clarify the hole-doping effect for the ${a}_{1g}{a}_{1g}$ singlet bond in ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$, we investigated Ti $3d$ orbital anisotropy between corundum-type ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$ and ilmenite-type ${\mathrm{MgTiO}}_{3}$ using linear dichroism of soft x-ray absorption spectroscopy of the Ti ${L}_{2,3}$ edge. From the linear dichroic spectral weight in ${\mathrm{Mg}}_{y}{\mathrm{Ti}}_{2\ensuremath{-}y}{\mathrm{O}}_{3}$, we confirmed that the ${a}_{1g}{a}_{1g}$ state is dominant not only in $y=0.01$ (almost ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$), but also in $y=0.29$, indicating that the Ti-Ti bond survives against a certain level of hole doping. In $y=0.63$ corresponding to 46% hole doping per Ti, the $3d$ orbital symmetry changes from ${a}_{1g}$ to ${e}_{g}^{\ensuremath{\pi}}$.

Corundum

10.1103/physrevb.108.195108

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Hole-doping-induced changes in the electronic structure ofLa1−xSrxFeO3

Physical Review B (2005)

Hiroki Wadati Daisuke Kobayashi Hiroshi Kumigashira Kozo Okazaki T. Mizokawa

We have studied the electronic structure of epitaxially grown thin films of La$_{1-x}$Sr$_x$FeO$_3$ by {\it in-situ} photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS) measurements. The Fe 2$p$ and valence-band PES spectra and the O $1s$ XAS spectra of LaFeO$_3$ have been successfully reproduced by configuration-interaction cluster-model calculation and, except for the satellite structure, by band-structure calculation.From the shift of the binding energies of core levels, the chemical potential was found to be shifted downward as $x$ was increased. Among the three peaks in the valence-band spectra of La$_{1-x}$Sr$_x$FeO$_3$, the peak nearest to the Fermi level ($E_F$), due to the ``$e_{g}$ band'', was found to move toward $E_F$ and became weaker as $x$ was increased, whereas the intensity of the peak just above $E_F$ in the O $1s$ XAS spectra increased with $x$. The gap or pseudogap at $E_F$ was seen for all values of $x$. These results indicate that changes in the spectral line shape around $E_F$ are dominated by spectral weight transfer from below to above $E_F$ across the gap and are therefore highly non-rigid-band-like.

X-ray absorption spectroscopy

Pseudogap

10.1103/physrevb.71.035108

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Citations (121)

Photoemission study of the itinerant-electron helimagnetFexCo1−xSi

Physical review. B, Condensed matter (2003)

Jaeseok Son Kozo Okazaki T. Mizokawa A. Fujimori T. Kanomata

${\mathrm{Fe}}_{x}{\mathrm{Co}}_{1\ensuremath{-}x}\mathrm{Si}$ is a metal with helical spin structure in the concentration range $0.2<x<0.95$ although the end members are a narrow-gap semiconductor (FeSi) and a diamagnetic semimetal (CoSi). We have studied the electronic structure of ${\mathrm{Fe}}_{x}{\mathrm{Co}}_{1\ensuremath{-}x}\mathrm{Si}(x=0.5,0.8)$ using ultraviolet photoemission spectroscopy. With Fe substitution for Co, the structure due to the transition-metal $3d$ states is shifted toward lower binding energies, qualitatively consistent with the prediction of the rigid-band model. Although the superposition of the spectra of FeSi and CoSi better describes the x dependence of the global spectral features than the rigid-band model, the x dependence near the Fermi level ${(E}_{F})$ is better described by the rigid-band model. The appearance of magnetic order in ${\mathrm{Fe}}_{x}{\mathrm{Co}}_{1\ensuremath{-}x}\mathrm{Si}$ may thus be explained by the rigid-band model, which predicts that the density of states at ${E}_{F}$ is low or zero for CoSi and FeSi but becomes large for intermediate x. We also find a weak temperature dependence around the Fermi level, qualitatively consistent with the increase in the electrical resistivity below the N\'eel temperature ${(T}_{N}).$

10.1103/physrevb.68.134447

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Citations (8)

ELECTRONIC STRUCTURE OF PEROVSKITE-TYPE MANGANESE OXIDES

WORLD SCIENTIFIC eBooks (1998)

A. Fujimori T. Mizokawa T. Saitoh

10.1142/9789812816795_0009

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Citations (1)