M. Taguchi

Nature of the well screened state in hard X-ray mn 2p core-level photoemission measurements of La1-xSrxMnO3 films

Using hard x-ray (HX; hnu=5.95 keV) synchrotron photoemission spectroscopy (PES), we study the intrinsic electronic structure of La(1-x)Sr(x)MnO(3) (LSMO) thin films. Comparison of Mn 2p core-levels with soft x-ray (SX; hnu approximately 1000 eV) PES shows a clear additional well-screened feature only in HX PES. Takeoff-angle dependent data indicate its bulk (> or =20 A) character. The doping and temperature dependence track the ferromagnetism and metallicity of the LSMO series. Cluster model calculations including charge transfer from doping-induced states show good agreement, confirming this picture of bulk properties reflected in Mn 2p core-levels using HX PES.

Theory of X-Ray Photoemission and X-Ray Emission Spectra in Mn Compounds

We analyze theoretically X-ray photoemission spectra (XPS) from Mn 2 p and 3 p core-levels in Mn compounds and Mn Kβ X-ray emission spectra (XES) by means of an MX 6 cluster model. In the calculation of 3 p -XPS and Kβ-XES, we take into account the effect of the term-dependent lifetime of the Mn 3 p core-hole due to the 3 p -3 d 3 d super-Coster-Kroning decay. The Kβ-XES is treated as a coherent second-order optical process, and the excitation spectra of Kβ-XES, which reflect the spin-dependent Mn 1 s absorption, are also calculated. It is shown that the effect of the core-hole potential plays an essential role in the excitation spectra of MnF 2 and MnO. The importance of the term-dependent lifetime of the final states is also pointed out.

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

Revisiting the valence-band and core-level photoemission spectra of NiO.

\sim

Photoemission evidence for a Mott-Hubbard metal-insulator transition in VO2

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

Coherent and Incoherent Excitations of Electron-Doped SrTiO3

_2

Probing the γ − α Transition in Bulk Ce under Pressure: A Direct Investigation by Resonant Inelastic X-Ray Scattering

CuO

Bulk screening in core-level photoemission from Mott-Hubbard and charge-transfer systems

_4

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

but is absent in Nd