A. Ashihara

High-resolution angle-resolved photoemission study of RSb (R=La, Ce, U)

Abstract High-resolution angle-resolved photoemission spectroscopy has been performed on isostructural RSbs (R=La, Ce, U) to study the electronic band structure near the Fermi level as well as the Fermi-surface topology. We found that USb has a metallic band structure in contrast with semimetallic LaSb and CeSb.

Magnetic phase transition of CeSb studied by high-resolution angle-resolved photoemission

We observed a change of Fermi-surface topology of CeSb across the magnetic phase transition using temperature-dependent high-resolution angle-resolved photoemission spectroscopy. The experimental results show that the complicated magnetic structure of CeSb strongly relates to its unique electronic structure as predicted by the anisotropic p-f mixing model.

High-resolution angle-resolved photoemission study of Sr14−xCaxCu2 4O4 1 (x=0 and 6)

Abstract We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) of ladder compounds Sr 14−x Ca x Cu 24 O41 (x= 0 and 6) to study the change of the electronic structure near the Fermi level (E F ) by substitution of Sr with Ca. The experimental band structures of both compounds determined by ARPES show a dispersive band near E F , which has a minimum binding energy at k a = (2n+1)π/2 (n=0, ±1, ±2...) with the periodicity of a ladder sublattice. This result indicates that the electronic states near E F originate in the ladder and from a Mott-Hubbard band with an energy gap at k a = (2n+1)π/2. This suggests that Cu atoms in the ladder take essentially a divalent state (Cu 2+ ) and “self-doped” holes reside on the chain. It was also found that the dispersive band of Sr 8 Ca 6 Cu 24 O 41 is closer to E F than that of Sr 14 Cu 24 O 41 , indicating that the ladder band is “doped” with holes by Ca-substitution. This suggests that the superconductivity observed in a heavily Ca-substituted sample occurs on the ladder.