32 research outputs found
Hybridization between the conduction band and 3d orbitals in the oxide-based diluted magnetic semiconductor InVO
The electronic structure of InVO () has been
investigated using photoemission spectroscopy (PES) and x-ray absorption
spectroscopy (XAS). The V core-level PES and XAS spectra revealed
trivalent electronic state of the V ion, consistent with the substitution of
the V ion for the In site. The V 3d partial density of states obtained by the
resonant PES technique showed a sharp peak above the O band. While the O
XAS spectrum of InVO was similar to that of InO,
there were differences in the In and 3d XAS spectra between V-doped and
pure InO. The observations give clear evidence for hybridization
between the In conduction band and the V 3d orbitals in InVO.Comment: 5 pages, 4 figure
Electronic structure and magnetism of the diluted magnetic semiconductor Fe-doped ZnO nano-particles
We have studied the electronic structure of ZnFeO
nano-particles, which have been reported to show ferromagnetism at room
temperature, by x-ray photoemission spectroscopy (XPS), resonant photoemission
spectroscopy (RPES), x-ray absorption spectroscopy (XAS) and x-ray magnetic
circular dichroism (XMCD). From the experimental and cluster-model calculation
results, we find that Fe atoms are predominantly in the Fe ionic state
with mixture of a small amount of Fe and that Fe ions are
dominant in the surface region of the nano-particles. It is shown that the room
temperature ferromagnetism in the ZnFeO nano-particles is
primarily originated from the antiferromagnetic coupling between unequal
amounts of Fe ions occupying two sets of nonequivalent positions in the
region of the XMCD probing depth of 2-3 nm.Comment: Single column, 12 pages, 8 figures, 1 tabl
Nature of magnetic coupling between Mn ions in as-grown GaMnAs studied by x-ray magnetic circular dichroism
The magnetic properties of as-grown GaMnAs have been
investigated by the systematic measurements of temperature and magnetic field
dependent soft x-ray magnetic circular dichroism (XMCD). The {\it intrinsic}
XMCD intensity at high temperatures obeys the Curie-Weiss law, but residual
spin magnetic moment appears already around 100 K, significantly above Curie
temperature (), suggesting that short-range ferromagnetic correlations are
developed above . The present results also suggest that antiferromagnetic
interaction between the substitutional and interstitial Mn (Mn) ions
exists and that the amount of the Mn affects .Comment: 4 pages, 4 figure
4f-derived Fermi Surfaces of CeRu2(Si[1-x]Ge[x])2 near the Quantum Critical Point: Resonant Soft X-ray ARPES Study
Angle-resolved photoelectron spectroscopy in the Ce 3d-4f excitation region
was measured for the paramagnetic state of CeRu2Si2, CeRu2(Si0.82Ge0.18)2, and
LaRu2Si2 to investigate the changes of the 4 electron Fermi surfaces around
the quantum critical point. While the difference of the Fermi surfaces between
CeRu2Si2 and LaRu2Si2 was experimentally confirmed, a strong 4f-electron
character was observed in the band structures and the Fermi surfaces of
CeRu2Si2 and CeRu2(Si0.82Ge0.18)2, consequently indicating a delocalized nature
of the 4 electrons in both compounds. The absence of Fermi surface
reconstruction across the critical composition suggests that SDW quantum
criticality is more appropriate than local quantum criticality in
CeRu2(Si[1-x]Ge[x])2.Comment: 4 pages, 5 figure
Simultaneous magnetic and chemical imaging of Nd-Fe-B thin films by means of XMCD-PEEM technique
Investigation of continuous changes in the electric-field-induced electronic state in Bi<inf>1-x</inf>Ca<inf>x</inf>FeO<inf>3-δ</inf>
Amongst the most interesting phenomena in correlated oxide systems are the doping-driven competitions between energetically similar ground states found in, e.g., high-Tc superconductors and colossal magnetoresistance manganites. It has recently been reported that doped multiferroics also exhibit this generic concept of phase competition. Here, we employ photoelectron emission microscopy (PEEM) to demonstrate evidence of systematic changes in the electronic structure of Bi1-xCaxFeO3-δ treated by electrically controlled hole carrier doping, the outcome of which clearly correlates with the local modulation of electronic conductivity observed in the same material. © the Partner Organisations 2014