arXiv subjects

A. Ino

Publications and source records attributed to A. Ino.

25 records · Page 2Linked to original sources

arXiv2000

Angle-resolved photoemission study of insulating and metallic Cu-O chains in PrBa$_2$Cu$_3$O$_7$ and PrBa$_2$Cu$_4$O$_8$

We compare the angle-resolved photoemission spectra of the hole-doped Cu-O chains in PrBa$_2$Cu$_3$O$_7$ (Pr123) and in PrBa$_2$Cu$_4$O$_8$ (Pr124). While, in Pr123, a dispersive feature from the chain takes a band maximum at $k_b$ (momentum along the chain) $\sim$ $π/4$ and loses its spectral weight around the Fermi level, it reaches the Fermi level at $k_b$ $\sim$ $π/4$ in Pr124. Although the chains in Pr123 and Pr124 are approximately 1/4-filled, they show contrasting behaviors: While the chains in Pr123 have an instability to charge ordering, those in Pr124 avoid it and show an interesting spectral feature of a metallic coupled-chain system.

cond-mat.str-el↗

arXiv2000

Electronic Structure of La2-xSrxCuO4 in the Vicinity of the Superconductor-Insulator Transition

We report on the result of angle-resolved photoemission (ARPES) study of La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) from an optimally doped superconductor ($x=0.15$) to an antiferromagnetic insulator ($x=0$). Near the superconductor-insulator transition (SIT) $x\sim 0.05$, spectral weight is transferred with hole doping between two coexisting components, suggesting a microscopic inhomogeneity of the doped-hole distribution. For the underdoped LSCO ($x\leq 0.12$), the dispersive band crossing the Fermi level becomes invisible in the $(0,0)-(π,π)$ direction unlike Bi$_2$Sr$_2$CaCu$_2$O$_{8+y}$. These observations may be reconciled with the evolution of holes in the insulator into fluctuating stripes in the superconductor.

cond-mat.supr-con↗

arXiv2000

Fermi Surface and Band Dispersion in La2-xSrxCuO4

Using angle-resolved photoemission spectroscopy (ARPES), we have observed the band structure, Fermi surface and their doping dependences in La2-xSrxCuO4. The results reveal that the Fermi surface undergoes a dramatic change: it is hole-like and centered at k=(pi,pi) in underdoped (x = 0.1) and optimally doped (x = 0.15) samples as in other cuprates while it is electron-like and centered at (0,0) in heavily overdoped (x = 0.3) ones. The peak in the ARPES spectra near (pi/2,pi/2) is broad and weak unlike in other cuprates. In the underdoped and optimally doped samples, a superconducting gap (Delta = 10 - 15 meV) is observed on the Fermi surface near (pi,0).

cond-mat.supr-con↗

arXiv1999

Photoemission Spectral Weight Transfer and Mass Renormalization in the Fermi-Liquid System La$_{1-x}$Sr$_x$TiO$_{3+y/2}$

We have performed a photoemission study of La$_{1-x}$Sr$_x$TiO$_{3+y/2}$ near the filling-control metal-insulator transition (MIT) as a function of hole doping. Mass renormalization deduced from the spectral weight and the width of the quasi-particle band around the chemical potential $μ$ is compared with that deduced from the electronic specific heat. The result implies that, near the MIT, band narrowing occurs strongly in the vicinity of $μ$. Spectral weight transfer occurs from the coherent to the incoherent parts upon antiferromagnetic ordering, which we associate with the partial gap opening at $μ$.

cond-mat.str-el↗

arXiv1999

Angle-resolved photoemission study of untwinned PrBa$_2$Cu$_3$O$_7$: undoped CuO$_2$ plane and doped CuO$_3$ chain

We have performed an angle-resolved photoemission study on untwinned PrBa$_2$Cu$_3$O$_7$, which has low resistivity but does not show superconductivity. We have observed a dispersive feature with a band maximum around ($π$/2,$π$/2), indicating that this band is derived from the undoped CuO$_2$ plane. We have observed another dispersive band exhibiting one-dimensional character, which we attribute to signals from the doped CuO$_3$ chain. The overall band dispersion of the one-dimensional band agrees with the prediction of $t-J$ model calculation with parameters relevant to cuprates except that the intensity near the Fermi level is considerably suppressed in the experiment.

cond-mat.str-el↗

arXiv1999

Doping Dependence of the Electronic Structure of Ba_{1-x}K_{x}BiO_{3} Studied by X-Ray Absorption Spectroscopy

We have performed x-ray absorption spectroscopy (XAS) and x-ray photoemission spectroscopy (XPS) studies of single crystal Ba_{1-x}K_{x}BiO_{3} (BKBO) covering the whole composition range $0 \leq x \leq 0.60$. Several features in the oxygen 1\textit{s} core XAS spectra show systematic changes with $x$. Spectral weight around the absorption threshold increases with hole doping and shows a finite jump between $x=0.30$ and 0.40, which signals the metal-insulator transition. We have compared the obtained results with band-structure calculations. Comparison with the XAS results of BaPb_{1-x}Bi_{x}O_{3} has revealed quite different doping dependences between BKBO and BPBO. We have also observed systematic core-level shifts in the XPS spectra as well as in the XAS threshold as functions of $x$, which can be attributed to a chemical potential shift accompanying the hole doping. The observed chemical potential shift is found to be slower than that predicted by the rigid band model based on the band-structure calculations.

cond-mat.supr-con↗

arXiv1998

Doping Dependent Density of States and Pseudogap Behavior in La2-xSrxCuO4

We have made a high-resolution photoemission study of La2-xSrxCuO4 in a wide hole concentration (x) range from a heavily overdoped metal to an undoped insulator. As x decreases, the spectral density of states at the chemical potential (μ) is suppressed with an x-dependence similar to the suppression of the electronic specific heat coefficient. In the underdoped region, the spectra show a pseudogap structure on the energy scale of 0.1 eV. The width of the pseudogap increases with decreasing x following the x-dependence of the characteristic temperatures of the magnetic susceptibility and the Hall coefficient.

cond-mat.supr-con↗