167 research outputs found
Orbital Subband Structures and Chiral Orbital Angular Momentum in the (001) Surface States of SrTiO
We have performed angle resolved photoemission spectroscopy (ARPES)
experiments on the surface states of SrTiO(001) using linearly and
circularly polarized light to investigate the subband structures of
out-of-plane orbitals and chiral orbital angular momentum (OAM).
The data taken in the first Brillouin zone reveal new subbands for
orbitals with Fermi wave vectors of 0.25 and 0.45 in
addition to the previously reported ones. As a result, there are at least two
subbands for all the Ti 3d t orbitals. Our circular dichroism ARPES data
is suggestive of a chiral OAM structure in the surface states and may provide
clues to the origin of the linear Rashba-like surface band splitting.Comment: 7 pages, 3 figures, Journal pape
Orbital selective Fermi surface shifts and mechanism of high T superconductivity in correlated AFeAs (A=Li,Na)
Based on the dynamical mean field theory (DMFT) and angle resolved
photoemission spectroscopy (ARPES), we have investigated the mechanism of high
superconductivity in stoichiometric LiFeAs. The calculated spectrum is in
excellent agreement with the observed ARPES measurement. The Fermi surface (FS)
nesting, which is predicted in the conventional density functional theory
method, is suppressed due to the orbital-dependent correlation effect with the
DMFT method. We have shown that such marginal breakdown of the FS nesting is an
essential condition to the spin-fluctuation mediated superconductivity, while
the good FS nesting in NaFeAs induces a spin density wave ground state. Our
results indicate that fully charge self-consistent description of the
correlation effect is crucial in the description of the FS nesting-driven
instabilities.Comment: 5 pages, 4 figures, supporting informatio
Orbital-selective confinement effect of Ru orbitals in SrRuO ultrathin film
The electronic structure of SrRuO thin film with thickness from 50 to 1
unit cell (u.c.) is investigated via the resonant inelastic x-ray scattering
(RIXS) technique at the O K-edge to unravel the intriguing interplay of orbital
and charge degrees of freedom. We found that orbital-selective quantum
confinement effect (QCE) induces the splitting of Ru orbitals. At the same
time, we observed a clear suppression of the electron-hole continuum across the
metal-to-insulator transition (MIT) occurring at the 4 u.c. sample. From these
two clear observations we conclude that QCE gives rise to a Mott insulating
phase in ultrathin SrRuO films. Our interpretation of the RIXS spectra is
supported by the configuration interaction calculations of RuO clusters.Comment: 7 pages, 7 figure
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