A5019045713- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Advanced Condensed Matter Physics
- Inorganic Chemistry and Materials
- Organic and Molecular Conductors Research
- Magnetic and transport properties of perovskites and related materials
- Superconductivity in MgB2 and Alloys
- Magnetism in coordination complexes
- Semiconductor materials and interfaces
- Magnetic Properties of Alloys
- High-pressure geophysics and materials
- Surface and Thin Film Phenomena
- Intellectual Capital and Performance Analysis
- Superconducting Materials and Applications
- Quantum and electron transport phenomena
- Topological Materials and Phenomena
- Corporate Taxation and Avoidance
- Diamond and Carbon-based Materials Research
- 2D Materials and Applications
- Inorganic Fluorides and Related Compounds
- Advanced Chemical Physics Studies
- Magnetic properties of thin films
- Electronic and Structural Properties of Oxides
- Advanced Chemical Sensor Technologies
Osaka Prefecture University
2013-2023
Osaka Metropolitan University
2022-2023
Hiroshima University
2009-2021
Osaka University
2010-2011
The nature of the pseudogap (PG) in high transition temperature (high Tc) superconducting cuprates has been a major issue condensed matter physics. It is still unclear whether Tc superconductivity can be universally associated with PG formation. Here we provide direct evidence existence phase via angle-resolved photoemission spectroscopy another family superconductor, iron pnictides. Our results reveal composition-dependent formation multiband electronic structure BaFe2(As1−xPx)2. develops...
In the hole-doped cuprates, a small amount of carriers suppresses antiferromagnetism and induces superconductivity. electron-doped on other hand, superconductivity appears only in narrow range high electron concentration ($\sim$ doped Ce content) after reduction annealing, strong antiferromagnetic (AFM) correlation persists superconducting phase. Recently, Pr$_{1.3-x}$La$_{0.7}$Ce$_{x}$CuO$_{4}$ (PLCCO) bulk single crystals annealed by "protect annealing" method showed $T_c$ $\sim$ 27 K for...
We have studied electronic structure of triangular lattice Ir$_{1-x}$Pt$_x$Te$_2$ superconductor using photoemission spectroscopy and model calculations. Ir $4f$ core-level spectra show that $5d$ $t_{2g}$ charge modulation established in the low temperature phase IrTe$_2$ is suppressed by Pt doping. This observation indicates suppression related to emergence superconductivity. Valence-band suggest accompanied orbital reconstruction. Based on results calculations, we argue orbitally-induced...
We report the first observation of multilayer band splitting in optimally doped trilayer cuprate Bi2Sr2Ca2Cu3O(10+δ) (Bi2223) by angle-resolved photoemission spectroscopy. The observed energy bands and Fermi surfaces are originated from outer inner CuO2 planes (OP IP). OP is overdoped with a large d-wave gap around node Δ0∼43 meV while IP underdoped an even Δ0∼60 meV. These gaps much larger than those for same doping level double-layer cuprates, which leads to Tc Bi2223. propose possible...
An energy gap is, in principle, a dominant parameter superconductivity. However, this view has been challenged for the case of high-Tc cuprates, because anisotropic evolution d-wave-like superconducting with underdoping difficult to formulate along critical temperature Tc. Here we show that nodal-gap 2ΔN closely follows 8.5 kBTc and is also proportional product an antinodal Δ(*) square-root superfluid density √Ps Bi₂Sr₂CaCu₂O₈+δ, using low-energy synchrotron-radiation angle-resolved...
We have determined the electron-coupling spectrum of superconducting ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ from high-resolution angle-resolved photoemission spectra by two deconvolution-free robust methods. As hole concentration decreases, coupling spectral weight at low energies $\ensuremath{\lesssim}15\text{ }\text{ }\mathrm{meV}$ shows a twofold and nearly band-independent enhancement, while that around $\ensuremath{\sim}65\text{...
We report an angle-resolved photoemission spectroscopy (ARPES) study on IrTe2 which exhibits interesting lattice distortion below 270 K and becomes triangular superconductors by suppressing the via chemical substitution or intercalation. ARPES results at 300 show multi-band Fermi surfaces with six-fold symmetry are basically consistent band structure calculations. At 20 in distorted phase, topology of inner is strongly modified distortion. The surface reconstruction depends orbital character...
We have performed a temperature-dependent angle-resolved photoemission spectroscopy (ARPES) study of the trilayer high-${T}_{c}$ cuprate superconductor (HTSC) Bi${}_{2}$Sr${}_{2}$Ca${}_{2}$Cu${}_{3}$O${}_{10+\ensuremath{\delta}}$ (Bi2223), and shown that ${T}_{c}$ (=110 K) ``effective'' superconducting gap ${\ensuremath{\Delta}}_{\mathrm{sc}}$ defined at end point Fermi arc follow relationship 2${\ensuremath{\Delta}}_{\mathrm{sc}}\ensuremath{\approx}4{k}_{\mathrm{B}}{T}_{c}$. Combining this...
We report peculiar momentum-dependent anisotropy in the superconducting gap observed by angle-resolved photoemission spectroscopy BaFe2(As1-xPx)2 (x = 0.30, Tc 30 K). Strongly anisotropic has been found only electron Fermi surface while on entire hole surfaces are nearly isotropic. These results inconsistent with horizontal nodes but consistent modified s± nodal loops. have shown that complicated modulation can be theoretically reproduced considering both spin and orbital fluctuations.
We report an angle-resolved photoemission spectroscopy (ARPES) study on a triangular lattice superconductor Ir$_{1-x}$Pt$_{x}$Te$_2$ in which the Ir-Ir or Te-Te bond formation, band Jahn-Teller effect, and spin-orbit interaction are cooperating competing with one another. The Fermi surfaces of substituted system qualitatively similar to structure calculations for undistorted IrTe$_2$ upward chemical potential shift due electron doping. A combination ARPES indicates that Te $5p$ removes...
Conventional superconductivity is caused by electron-phonon coupling. The discovery of high-temperature superconductors raised the question whether such strong coupling realized in cuprates. Strong with some collective excitation mode has been indicated a dispersion "kink". However, there intensive debate regarding relevant magnetic resonance or an oxygen buckling phonon mode. This ambiguity consequence energy main prominent kink. Here, we show new landscape kinks. We report that heavily...
Using high-resolution angle-resolved photoemission spectroscopy, we elucidate the Rashba splitting of $\ensuremath{\Delta}{k}_{F}=0.003$ ${\AA{}}^{\ensuremath{-}1}$ near Fermi level (${E}_{F}$) in Shockley surface state Cu(110) at $\overline{\mathrm{Y}}$ point Brillouin zone. The observed energy-band dispersion exhibits a kink structure $\ensuremath{\sim}\ensuremath{-}20$ meV, which is clear indication band renormalization caused by an electron-phonon interaction. coupling parameter found to...
We investigated the bulk-derived electronic structure of temperature-induced valence transition system ${\mathrm{EuNi}}_{2}$(${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$)${}_{2}$ ($x=0.70$, 0.79, and 0.82) by means hard x-ray photoemission spectroscopy (HAXPES). The HAXPES spectra clearly show distinct temperature dependencies in spectral intensities ${\mathrm{Eu}}^{2+}$ ${\mathrm{Eu}}^{3+}\phantom{\rule{4pt}{0ex}}3d$ components. For $x=0.70$, changes components with reflect a...
We report an investigation on the mixed-valence state for $\mathrm{Yb}X{\mathrm{Cu}}_{4}$ compounds with $X$ = Mg, Cd, In, and Sn. The x-ray diffraction measurements Sn have revealed a cubic ${\mathrm{AuBe}}_{5}$-type structure lattice constant $a=7.123\phantom{\rule{4pt}{0ex}}\AA{}$. Kondo temperature of is determined to be ${T}_{\mathrm{K}}=503$ K from value magnetic susceptibility. observed mixing ${\mathrm{Yb}}^{2+}$ ${\mathrm{Yb}}^{3+}$ electronic states absorption spectra at 300 change...
Hybridization of Bogoliubov quasiparticles (BQPs) between the CuO_{2} layers in triple-layer cuprate high-temperature superconductor Bi_{2}Sr_{2}Cu_{2}Cu_{3}O_{10+δ} is studied by angle-resolved photoemission spectroscopy (ARPES). In superconducting state, an anticrossing gap opens outer- and inner-BQP bands, which we attribute primarily to interlayer single-particle hopping with possible contributions from Cooper pairing. We find that d-wave both BQP bands smoothly develops momentum without...
We have carried out hard x-ray photoemission spectroscopy (HAXPES) of Yb1-x Zr x B12 ([Formula: see text]) to study the effects electron doping on Kondo insulator YbB12. The Yb valences at 300 K estimated from 3d HAXPES spectra decreased after substituting with 2.93 for YbB12 2.83 Yb0.125Zr0.875B12. A temperature dependent valence decrease was found upon cooling all concentrations. peak shifts B 1s and 3d5/2, Yb3+ 4f toward deeper binding-energy increasing concentration, which indicates a...
Photoemission spectroscopy with low-energy tunable photons on oxygen-deficient iron-based oxypnictide superconductors NdFeAsO 0.85 ( T c =52 K) reveals a distinct photon-energy dependence of the electronic structure near Fermi level E F ). A clear shift leading-edge can be observed in superconducting states 9.5 eV photons, while cutoff little 6.0 photons. The results are indicative gap opening not hole-like ones around Γ(0,0) point but electron-like sheets M(π,π) point.
The electronic structure of Yb-based Kondo lattices ${\mathrm{Yb}}_{2}{\mathrm{Pt}}_{6}{X}_{15}$ ($X$=Al, Ga) has been investigated by means photoemission spectroscopy using hard x-ray ($h\ensuremath{\nu}=5.95$ keV) and vacuum ultraviolet ($h\ensuremath{\nu}=182$ eV) synchrotron radiation. Yb $3d$ spectra showed both ${\mathrm{Yb}}^{2+}$- ${\mathrm{Yb}}^{3+}$-derived structures, directly indicating valence fluctuation. valences ${\mathrm{Yb}}_{2}{\mathrm{Pt}}_{6}{\mathrm{Al}}_{15}$ were...
Highly one-dimensional (1D) Fermi sheets are realized at the surface of a layered Ir telluride IrTe2 which exhibits stripe-type charge and orbital order below ∼280 K. The 1D appear in low temperature range where stripe is well established. truncated by bulk surfaces, spectral weight suppression level deviates from typical Tomonaga–Luttinger behavior. band runs along accompanied several branches can be derived quantization perpendicular direction.
We report a temperature-dependent study of Kondo resonance in the heavy-fermion compounds $\mathrm{Yb}X{\mathrm{Cu}}_{4}$ with $X=\mathrm{Mg}$, Cd, and Sn. A sharp peak ${\mathrm{Yb}}^{2+}\phantom{\rule{4pt}{0ex}}4{f}_{7/2}$ state has been observed photoemission spectra, its energy position limit zero temperature is agreement scale ${T}_{\mathrm{K}}$. The develops form dispersionless large spectral weight at ${T}_{\mathrm{coh}}$ well below onset robust comparable to local maximum magnetic...