Polarization resolved Cu L3L_3-edge resonant inelastic x-ray scattering of orbital and spin excitations in NdBa2_{2}Cu3_{3}O7−δ_{7-\delta}

High resolution resonant inelastic x-ray scattering (RIXS) has proven particularly effective in the determination of crystal field and spin excitations in cuprates. Its strength lies in the large Cu $L_{3}$ resonance and in the fact that the scattering cross section follows quite closely the single-ion model predictions, both in the insulating parent compounds and in the superconducting doped materials. However, the spectra become increasingly broader with (hole) doping, hence resolving and assigning spectral features has proven challenging even with the highest energy resolution experimentally achievable. Here we have overcome this limitation by measuring the complete polarization dependence of the RIXS spectra as function of momentum transfer and doping in thin films of NdBa$_{2}$Cu$_{3}$O$_{7-\delta}$. Besides confirming the previous assignment of $dd$ and spin excitations (magnon, bimagnon) in the antiferromagnetic insulating parent compound, we unequivocally single out the actual spin-flip contribution at all dopings. We also demonstrate that the softening of $dd$ excitations is mainly attributed to the shift of the $xy$ peak to lower energy loss. These results provide a definitive assessment of the RIXS spectra of cuprates and demonstrate that RIXS measurements with full polarization control are practically feasible and highly informative.Comment: 14 pages, 10 figure

The simultaneous measurement of energy and linear polarization of the scattered radiation in resonant inelastic soft x-ray scattering

Resonant Inelastic X-ray Scattering (RIXS) in the soft x-ray range is an element-specific energy-loss spectroscopy used to probe the electronic and magnetic excitations in strongly correlated solids. In the recent years, RIXS has been progressing very quickly in terms of energy resolution and understanding of the experimental results, but the interpretation of spectra could further improve, sometimes decisively, from a full knowledge of the polarization of incident and scattered photons. Here we present the first implementation, in a high resolution RIXS spectrometer used to analyze the scattered radiation, of a device allowing the measurement of the degree of linear polarization. The system, based on a graded W/B4C multilayer mirror installed in proximity of the CCD detector, has been installed on the AXES spectrometer at the ESRF; it has been fully characterized and it has been used for a demonstration experiment at the Cu L3 edge on a high-Tc superconducting cuprate. The loss in efficiency suffered by the spectrometer equipped with this test facility was a factor 17.5. We propose also a more advanced version, suitable for a routine use on the next generation of RIXS spectrometers and with an overall efficiency up to 10%.Comment: 26 pages, 8 figure

FMR studies of magnetic properties of Co and Fe thin films on Al 2O3 and MgO substrates

The effect of substrates on the magnetic properties has been studied for Co and Fe films both on Al2O3 (112̄0) and MgO (001) substrates by using ferromagnetic resonance techniques. For Fe(001)/MgO(001) samples the thickness dependence of the magnetocrystalline constant and of the effective magnetization values have been determined from the in-plane angular variation of the resonance field H0. Different reasons for the thickness dependencies of these parameters are discussed. For Co(111)/Al 2O3(112̄0) the angular variation of H0 exhibits an uniaxial anisotropy, for which several causes are discussed. For Co(112̄0)/MgO(100) a four-fold in-plane anisotropy was observed which is due to the twinned structure of these samples

Minimally invasive bunionette correction

Bunionette or 'tailor's bunion' is a deformity of the fifth ray, which comes along with a metatarsus quintus valgus and a varus deformity of the fifth toe with subluxation of the metatarsophalangeal joint. A minimally invasive osteotomy of the fifth metatarsal without internal fixation using burrs is an increasingly used alternative for symptomatic tailor's bunion deformity. Similar to open surgery procedures the type of osteotomy complies with the underlying pathology. Minimally invasive surgical (MIS) procedures allow comprehensive treatment of various types of tailor's bunion deformities. Symptomatic tailor's bunion deformity, failed conservative treatment, a closed epiphyseal gap. Osteoporotic bone, poor patient compliance. The technique comprises percutaneous resection of the lateral exostosis of the fifth metatarsal head with a straight burr and an osteotomy of the fifth metatarsal, either distally, diaphyseal or proximally with a conical burr due to the shape of the deformity, usually without internal fixation. Redressive wrapping, partial pain-adapted weight bearing. Non-steroidal anti-inflammatory drugs for 3-5 days, lymphatic drainage, intermittent cooling. Radiographic assessment on postoperative day 1; radiographic follow-up 6 weeks postoperatively. Thromboembolic prophylaxis. The clinical outcome is comparable to standard surgical procedures with the advantages of MIS. Based on our results and the current literature, the minimally invasive distal metatarsal osteotomy without fixation is becoming a reliable treatment for tailor's bunion

Graded multilayers for fully polarization resolved Resonant Inelastic X-ray Scattering in the soft x-ray range

On the upgraded ESRF soft x-ray beamline ID32 a new spectrometer for Resonant X-ray Inelastic Scattering (RIXS) will be installed. To operate in fully polarized mode, a polarimeter will be inserted in the instrument to measure simultaneously the energy spectra and the linear polarization. The new spectrometer works between 500 eV and 1000 eV and requires graded multilayers to optimize the energy tunability and the polarization sensitivity. The present work covers the design, the fabrication, and the characterization of the multilayers. Performance evaluations during test and commissioning experiments with soft x-rays complement the paper

FMR studies of magnetic properties of Co and Fe thin films on Al 2O3 and MgO substrates

The effect of substrates on the magnetic properties has been studied for Co and Fe films both on Al2O3 (112̄0) and MgO (001) substrates by using ferromagnetic resonance techniques. For Fe(001)/MgO(001) samples the thickness dependence of the magnetocrystalline constant and of the effective magnetization values have been determined from the in-plane angular variation of the resonance field H0. Different reasons for the thickness dependencies of these parameters are discussed. For Co(111)/Al 2O3(112̄0) the angular variation of H0 exhibits an uniaxial anisotropy, for which several causes are discussed. For Co(112̄0)/MgO(100) a four-fold in-plane anisotropy was observed which is due to the twinned structure of these samples

FMR studies of magnetic properties of Co and Fe thin films on Al 2O3 and MgO substrates

The effect of substrates on the magnetic properties has been studied for Co and Fe films both on Al2O3 (112̄0) and MgO (001) substrates by using ferromagnetic resonance techniques. For Fe(001)/MgO(001) samples the thickness dependence of the magnetocrystalline constant and of the effective magnetization values have been determined from the in-plane angular variation of the resonance field H0. Different reasons for the thickness dependencies of these parameters are discussed. For Co(111)/Al 2O3(112̄0) the angular variation of H0 exhibits an uniaxial anisotropy, for which several causes are discussed. For Co(112̄0)/MgO(100) a four-fold in-plane anisotropy was observed which is due to the twinned structure of these samples