1,912 research outputs found
Bimagnon studies in cuprates with Resonant Inelastic X-ray Scattering at the O K edge. II - The doping effect in La2-xSrxCuO4
We present RIXS data at O K edge from La2-xSrxCuO4 vs. doping between x=0.10
and x=0.22 with attention to the magnetic excitations in the Mid-Infrared
region. The sampling done by RIXS is the same as in the undoped cuprates
provided the excitation is at the first pre-peak induced by doping. Note that
this excitation energy is about 1.5 eV lower than that needed to see bimagnons
in the parent compound. This approach allows the study of the upper region of
the bimagnon continuum around 450 meV within about one third of the Brilluoin
Zone around \Gamma. The results show the presence of damped bimagnons and of
higher even order spin excitations with almost constant spectral weight at all
the dopings explored here. The implications on high Tc studies are briefly
addressed
Paramagnon dispersion in -FeSe observed by Fe -edge resonant inelastic x-ray scattering
We report an Fe -edge resonant inelastic x-ray scattering (RIXS) study of
the unusual superconductor -FeSe. The high energy resolution of this
RIXS experiment (55meV FWHM) made it possible to resolve
low-energy excitations of the Fe manifold. These include a broad peak
which shows dispersive trends between 100-200meV along the and
directions of the one-Fe square reciprocal lattice, and which can
be attributed to paramagnon excitations. The multi-band valence state of FeSe
is among the most metallic in which such excitations have been discerned by
soft x-ray RIXS
Similar temperature scale for valence changes in Kondo lattices with different Kondo temperatures
The Kondo model predicts that both the valence at low temperatures and its
temperature dependence scale with the characteristic energy T_K of the Kondo
interaction. Here, we study the evolution of the 4f occupancy with temperature
in a series of Yb Kondo lattices using resonant X-ray emission spectroscopy. In
agreement with simple theoretical models, we observe a scaling between the
valence at low temperature and T_K obtained from thermodynamic measurements. In
contrast, the temperature scale T_v at which the valence increases with
temperature is almost the same in all investigated materials while the Kondo
temperatures differ by almost four orders of magnitude. This observation is in
remarkable contradiction to both naive expectation and precise theoretical
predictions of the Kondo model, asking for further theoretical work in order to
explain our findings. Our data exclude the presence of a quantum critical
valence transition in YbRh2Si2
High-resolution resonant inelastic soft X-ray scattering as a probe of the crystal electrical field in lanthanides demonstrated for the case of CeRh2Si2
The magnetic properties of rare earth compounds are usually well captured by
assuming a fully localized f shell and only considering the Hund's rule ground
state multiplet split by a crystal electrical field (CEF). Currently, the
standard technique for probing CEF excitations in lanthanides is inelastic
neutron scattering. Here we show that with the recent leap in energy
resolution, resonant inelastic soft X-ray scattering has become a serious
alternative for looking at CEF excitations with some distinct advantages
compared to INS. As an example we study the CEF scheme in CeRh2Si2, a system
that has been intensely studied for more than two decades now but for which no
consensus has been reached yet as to its CEF scheme. We used two new features
that have only become available very recently in RIXS, high energy resolution
of about 30 meV as well as polarization analysis in the scattered beam, to find
a unique CEF description for CeRh2Si2. The result agrees well with previous INS
and magnetic susceptibility measurements. Due to its strong resonant character,
RIXS is applicable to very small samples, presents very high cross sections for
all lanthanides, and further benefits from the very weak coupling to phonon
excitation. The rapid progress in energy resolution of RIXS spectrometers is
making this technique increasingly attractive for the investigation of the CEF
scheme in lanthanides
Sensory innervation of the guinea pig colon and rectum compared using retrograde tracing and immunohistochemistry.
Embargoed until 2 April 2017 as per publisher's policy
Impact of the National Institute for Health and Care Excellence (NICE) guidance on medical technology uptake: analysis of the uptake of spinal cord stimulation in England 2008-2012.
This is the final version of the article. Available from the publisher via the DOI in this record.BACKGROUND: The National Institute for Health and Care Excellence (NICE) Technology Appraisal Guidance on spinal cord stimulation (SCS) was published in 2008 and updated in 2012 with no change. This guidance recommends SCS as a cost-effective treatment for patients with neuropathic pain. OBJECTIVE: To assess the impact of NICE guidance by comparing SCS uptake in England pre-NICE (2008-2009) and post-NICE (2009-2012) guidance. We also compared the English SCS uptake rate with that of Belgium, the Netherlands, France and Germany. DESIGN: SCS implant data for England was obtained from the Hospital Episode Statistics (HES) database and compared with other European countries where comparable data were available. RESULTS: The HES data showed small increases in SCS implantation and replacement/revision procedures, and a large increase in SCS trials between 2008 and 2012. The increase in the total number of SCS procedures per million of population in England is driven primarily by revision/replacements and increased trial activity. Marked variability in SCS uptake at both health regions and primary care trust level was observed. CONCLUSIONS: Despite the positive NICE recommendation for the routine use of SCS, we found no evidence of a significant impact on SCS uptake in England. Rates of SCS implantation in England are lower than many other European countries.Access to the QUANTIS database to extract the relevant Hospital
Episode Statistics data was funded by Medtronic UK
Exchange Splitting and Charge Carrier Spin Polarization in EuO
High quality thin films of the ferromagnetic semiconductor EuO have been
prepared and were studied using a new form of spin-resolved spectroscopy. We
observed large changes in the electronic structure across the Curie and
metal-insulator transition temperature. We found that these are caused by the
exchange splitting of the conduction band in the ferromagnetic state, which is
as large as 0.6 eV. We also present strong evidence that the bottom of the
conduction band consists mainly of majority spins. This implies that doped
charge carriers in EuO are practically fully spin polarized.Comment: 4 pages, 5 figure
Single 3 transition metal atoms on multi-layer graphene systems: electronic configurations, bonding mechanisms and role of the substrate
The electronic configurations of Fe, Co, Ni, and Cu adatoms on graphene and
graphite have been studied by x-ray magnetic circular dichroism and charge
transfer multiplet theory. A delicate interplay between long-range interactions
and local chemical bonding is found to influence the adatom equilibrium
distance and magnetic moment. The results for Fe and Co are consistent with
purely physisorbed species having, however, different 3-shell occupancies on
graphene and graphite ( and , respectively). On the other hand,
for the late 3 metals Ni and Cu a trend towards chemisorption is found,
which strongly quenches the magnetic moment on both substrates.Comment: 7 pages, 4 figure
Orbital occupation and magnetic moments of tetrahedrally coordinated iron in CaBaFe4O7
CaBaFe4O7 is a mixed-valent transition metal oxide having both Fe2+ and Fe3+
ions in tetrahedral coordination. Here we characterize its magnetic properties
by magnetization measurements and investigate its local electronic structure
using soft x-ray absorption spectroscopy at the Fe L2,3 edges, in combination
with multiplet cluster and spin-resolved band structure calculations. We found
that the Fe2+ ion in the unusual tetrahedral coordination is Jahn-Teller active
with the high-spin e^2 (up) t2^3 (up) e^1 (down) configuration having a
x^2-y^2-like electron for the minority spin. We deduce that there is an
appreciable orbital moment of about L_z=0.36 caused by multiplet interactions,
thereby explaining the observed magnetic anisotropy. CaBaFe4O7, a member of the
'114' oxide family, offers new opportunities to explore charge, orbital and
spin physics in transition metal oxides
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