Magneto-optic Kerr effect in a spin-polarized zero-moment ferrimagnet

The magneto-optical Kerr effect (MOKE) is often assumed to be proportional to the magnetisation of a magnetically ordered metallic sample; in metallic ferrimagnets with chemically distinct sublattices, such as rare-earth transition-metal alloys, it depends on the difference between the sublattice contributions. Here we show that in a highly spin polarized, fully compensated ferrimagnet, where the sublattices are chemically similar, MOKE is observed even when the net moment is strictly zero. We analyse the spectral ellipsometry and MOKE of Mn 2 Ru x Ga, and show that this behaviour is due to a highly spin-polarized conduction band dominated by one of the two manganese sublattices which creates helicity-dependent reflectivity determined by a broad Drude tail. Our findings open new prospects for studying spin dynamics in the infra-red.Comment: 7 pages, 7 figure

An in Situ Study of Precursor Decomposition via Refractive Index Sensing in p-Type Transparent Copper Chromium Oxide

Oxide semiconductors are penetrating into a wide range of energy, environmental, and electronic applications, possessing a potential to outrun currently employed semiconductors. However, an insufficient development of p-type oxides is a major obstacle against complete oxide electronics. Quite often oxide deposition is performed by the spray pyrolysis method, inexpensive to implement and therefore accessible to a large number of laboratories. Although, the complex growth chemistry and a lack of in situ monitoring during the synthesis process can complicate the growth optimization of multicomponent oxides. Here we present a concept of plasmonic, optical sensing that has been applied to spray pyrolysis oxide film growth monitoring for the first time. The proposed method utilizes a polarization based refractive index sensing platform using Au nanodimers as transducing elements. As a proof of concept, the changes in the refractive index of the grown film were extracted from individual Cu(acac)2 and Cr(acac)3 precursors in real time to reveal their thermal decomposition processes. Obtained activation energies give insight into the physical origin of the narrow temperature window for the synthesis of high performing p-type transparent conducting copper chromium oxide CuxCrO2. The versatility of the proposed method makes it effective in the growth rate monitoring of various oxides, exploring new candidate materials and optimizing the synthesis conditions for acquisition of high performing oxides synthesized by a high throughput cost-effective method

Crystallographic characterisation of ultra-thin, or amorphous transparent conducting oxides:the case for raman spectroscopy.

The electronic and optical properties of transparent conducting oxides (TCOs) are closely linked to their crystallographic structure on a macroscopic (grain sizes) and microscopic (bond structure) level. With the increasing drive towards using reduced film thicknesses in devices and growing interest in amorphous TCOs such as n-type InGaZnO 4 (IGZO), ZnSnO 3 (ZTO), p-type Cu x CrO 2 , or ZnRh 2 O 4 , the task of gaining in-depth knowledge on their crystal structure by conventional X-ray diffraction-based measurements are becoming increasingly difficult. We demonstrate the use of a focal shift based background subtraction technique for Raman spectroscopy specifically developed for the case of transparent thin films on amorphous substrates. Using this technique we demonstrate, for a variety of TCOs CuO, a-ZTO, ZnO:Al), how changes in local vibrational modes reflect changes in the composition of the TCO and consequently their electronic properties

Serum 25-hydroxyvitamin D, calcium and parathyroid hormone levels in Native and European populations in Greenland

AbstractCa homoeostasis is important to human health and tightly controlled by powerful hormonal mechanisms that display ethnic variation. Ethnic variations could occur also in Arctic populations where the traditional Inuit diet is low in Ca and sun exposure is limited. We aimed to assess factors important to parathyroid hormone (PTH) and Ca in serum in Arctic populations. We included Inuit and Caucasians aged 50–69 years living in the capital city in West or in rural East Greenland. Lifestyle factors were assessed by questionnaires. The intake of Inuit diet was assessed from a FFQ. 25-Hydroxyvitamin D (25OHD2and 25OHD3) levels were measured in serum as was albumin, Ca and PTH. The participation rate was 95 %, with 101 Caucasians and 434 Inuit. Median serum 25OHD (99·7 % was 25OHD3) in Caucasians/Inuit was 42/64 nmol/l (25, 75 percentiles 25, 54/51, 81) (P&lt;0·001). Total Ca in serum was 2·33/2·29 mmol/l (25, 75 percentiles 2·26, 2·38/2·21, 2·36) (P=0·01) and PTH was 2·7/2·2 pmol/l (25, 75 percentiles 2·2, 4·1/1·7, 2·7) (P&lt;0·001). The 69/97 Caucasians/Inuit with serum 25OHD &lt;50 nmol/l differed in PTH (P=0·001) that rose with lower 25OHD levels in Caucasians, whereas this was not the case in Inuit. Ethnic origin influenced PTH (β=0·27,P&lt;0·001) and Ca (β=0·22,P&lt;0·001) in multivariate linear regression models after adjustment for age, sex, BMI, smoking, alcohol and diet. In conclusion, ethnic origin influenced PTH, PTH response to low vitamin D levels and Ca levels in populations in Greenland. Recommendations are to evaluate mechanisms underlying the ethnic influence on Ca homoeostasis and to assess the impact of transition in dietary habits on Ca homoeostasis and skeletal health in Arctic populations.</jats:p

Oxidation of Nb(110): atomic structure of the NbO layer and its influence on further oxidation.

NbO terminated Nb(110) and its oxidation are examined by scanning tunneling microscopy and spectroscopy (STS). The oxide structures are strongly influenced by the structural and electronic properties of the underlying NbO substrate. The NbO is terminated by one-dimensional few-nanometer nanocrystals, which form an ordered pattern. High-resolution STS measurements reveal that the nanocrystals and the regions between the nanocrystals exhibit different electronic characters. Low-dosage oxidation, sufficient for sub-monolayer coverage of the NbO, with subsequent UHV annealing results in the formation of resolved sub-nanometer clusters, positioned in-between the nanocrystals. Higher dosage oxidation results in the formation of a closed Nb2O5-y layer, which is confirmed by X-ray photoelectron spectroscopy measurements. The pentoxide is amorphous at the atomic-scale. However, large scale (tens of nanometers) structures are observed with their symmetry matching that of the underlying nanocrystals

Investigating the morphology, hardness, and porosity of copper filters produced via Hydraulic Pressing

This paper presents an examination of the production of copper air filters via the Hydraulic Pressing (HP) method. Processing conditions examined included powder particle type (spherical and dendritic), varying compaction pressures (635, 714, and 793 MPa) and different pore forming (polyvinyl alcohol (PVA)) concentrations (1, 2, and 3 wt.%). Following compaction, the samples were thermally sintered in a two stage sintering regime at 200 ◦C and 750 ◦C. The morphology, porosity, and mechanical properties of the sintered samples were characterised. Morphological analysis demonstrated better consolidation and over-lapping of the copper powder particles in samples with a higher weight percentage of the PVA. Highest porosity was achieved in the sample produced using the dendritic copper powder mixed with highest weight percentage of PVA. As the samples were very porous, the hardness of the samples varied greatly. Samples prepared with spherical powders at high pressure demonstrated the highest hardness. The results in this study show that copper filters with 14%e26% porosity can effectively be produced using spherical and dendritic copper powders by controlling the compaction pressure and PVA concentration

Tailored CuCl2 nanoparticles for glutamine and ammonia biochemical sensing applications

In this study, CuCl2 nanoparticles (NPs) synthesised via pulsed laser ablation in liquid (PLAL) were successfully employed to simultaneously detect glutamine and ammonia, with a limit of detection of 20Â nM and up to 1500Â ppm, respectively. These NPs hold potential for non-invasive diagnosis and monitoring of various health conditions using urine and sweat samples. The sensing mechanism relied on the plasmon peaks of CuCl2 NPs in the UV range (at 300, 363, and 423Â nm), which were used to correlate the levels of glutamine and ammonia concentration with the absorbance. Quasi-spherical CuO and pyramidal CuCl2 NPs were synthesised through laser ablation of Cu powder in liquid IPA and IPA-HCl, respectively. CuCl2 NPs displayed higher ablation efficiency, higher optical absorbance (20-fold), and an 8400-fold increase in colloidal conductivity (0.0005 vs 4.2Â mS/cm) compared to CuO NPs. The NP size distribution ranged broadly from 10Â nm to less than 100Â nm. XPS analysis revealed that ablation in pure IPA resulted in oxidized Cu NPs, while ablation in IPA-HCl liquid medium (12Â nM HCl) led to the formation of a combination of metallic copper and CuCl2 NPs that were more conductive and had higher optical absorbance than their oxidized counterparts

Silver nanocolloid generation using dynamic laser ablation synthesis in solution system and drop-casting

Conductive inks allow for low cost and scalable deposition of conductive tracks and patterns for printed electronics. Metal nanoparticle colloids are a novel form for producing conductive inks. Laser Ablation Synthesis in Solution (LASiS) is a “green” method for the production of metal nanoparticle colloids without the need for environmentally hazardous chemicals, however the method has typically been limited by its low production rates. This study reports on the generation of an additive free silver nanocolloid with maximized productivity using a flow-based LASiS system and its characterization using dynamic light scattering, UV–VIS, transmission electron microscopy and field emission scanning electron microscopy. The productivity of the LASiS silver nanoparticle (size 34 ± 5 nm) was 0.9 mg mL−1. While the flow-based system achieves high laser ablation rates in the mass of nanomaterial generated per unit time, the volume of liquid required for the flow leads to relatively low concentrations. Therefore, in this work, LASiS concentrated ink was formulated via a centrifugal method, which was then drop-cast and heat treated to produce a conductive silver layer. Centrifuging to concentrate the ink was shown to be a necessary step to achieve good results, with the lowest resistance across the drop-cast material of 60.2 after annealing