Masaharu Matsunami

Strong valence fluctuation in the quantum critical heavy fermion superconductor β-YbAlB4: a hard x-ray photoemission study.

Electronic structures of the quantum critical superconductor β-YbAlB4 and its polymorph α-YbAlB4 are investigated by using bulk-sensitive hard x-ray photoemission spectroscopy. From the Yb 3d core level spectra, the values of the Yb valence are estimated to be ∼2.73 and ∼2.75 for α- and β-YbAlB4, respectively, thus providing clear evidence for valence fluctuations. The valence band spectra of these compounds also show Yb2+ peaks at the Fermi level. These observations establish an unambiguous case of a strong mixed valence at quantum criticality for the first time among heavy fermion systems, calling for a novel scheme for a quantum critical model beyond the conventional Doniach picture in β-YbAlB4.

Evidence for Suppressed Screening on the Surface of High Temperature La2-xSrxCuO4 and Nd2-xCexCuO4 Superconductors

Hard X-ray Photoemission spectroscopy (PES) of copper core electronic states, with a probing depth of

Coherent and Incoherent Excitations of Electron-Doped SrTiO3

\sim

Femtosecond core-level photoemision spectroscopy on 1T-TaS2 using a 60-eV laser source

60 \AA, is used to show that the Zhang-Rice singlet feature is present in La

Optical study of charge instability in CeRu2Al10 in comparison with CeOs2Al10 and CeFe2Al10

_2

Evidence for a correlated insulator to antiferromagnetic metal transition in CrN.

CuO

Time-resolved HAXPES at SACLA: probe and pump pulse-induced space-charge effects

_4

Warping effects in the band and angular-momentum structures of the topological insulator Bi2Te3

but is absent in Nd

Gap Formation in the Filled Skutterudite CeOs4Sb12

_2

Pressure tuning of an ionic insulator into a heavy electron metal: an infrared study of YbS.

CuO