Contiguous 3d and 4f magnetism: towards strongly correlated 3d electrons in YbFe2Al10

We present magnetization, specific heat, and 27Al NMR investigations on YbFe2Al10 over a wide range in temperature and magnetic field. The magnetic susceptibility at low temperatures is strongly enhanced at weak magnetic fields, accompanied by a ln(T0/T) divergence of the low-T specific heat coefficient in zero field, which indicates a ground state of correlated electrons. From our hard X-ray photo emission spectroscopy (HAXPES) study, the Yb valence at 50 K is evaluated to be 2.38. The system displays valence fluctuating behavior in the low to intermediate temperature range, whereas above 400 K, Yb3+ carries a full and stable moment, and Fe carries a moment of about 3.1 mB. The enhanced value of the Sommerfeld Wilson ratio and the dynamic scaling of spin-lattice relaxation rate divided by T [27(1/T1T)] with static susceptibility suggests admixed ferromagnetic correlations. 27(1/T1T) simultaneously tracks the valence fluctuations from the 4f -Yb ions in the high temperature range and field dependent antiferromagnetic correlations among partially Kondo screened Fe 3d moments at low temperature, the latter evolve out of an Yb 4f admixed conduction band.Comment: To appear in Phys. Rev. Let

Structural and magnetic properties of E-Fe_{1-x}Co_xSi thin films deposited via pulsed laser deposition

We report pulsed laser deposition synthesis and characterization of polycrystalline Fe1-xCox Si thin films on Si (111). X-ray diffraction, transmission electron, and atomic force microscopies reveal films to be dense, very smooth, and single phase with a cubic B20 crystal structure. Ferromagnetism with significant magnetic hysteresis is found for all films including nominally pure FeSi films in contrast to the very weak paramagnetism of bulk FeSi. For Fe1-xCoxSi this signifies a change from helimagnetism in bulk, to ferromagnetism in thin films. These ferromagnetic thin films are promising as a magnetic-silicide/silicon system for polarized current production, manipulation, and detection.Comment: 12 pages, 4 figures accepted in the Applied Physics Letter

Sequential localization of a complex electron fluid

Complex and correlated quantum systems with promise for new functionality often involve entwined electronic degrees of freedom. In such materials, highly unusual properties emerge and could be the result of electron localization. Here, a cubic heavy fermion metal governed by spins and orbitals is chosen as a model system for this physics. Its properties are found to originate from surprisingly simple low-energy behavior, with two distinct localization transitions driven by a single degree of freedom at a time. This result is unexpected, but we are able to understand it by advancing the notion of sequential destruction of an SU(4) spin-orbital-coupled Kondo entanglement. Our results implicate electron localization as a unified framework for strongly correlated materials and suggest ways to exploit multiple degrees of freedom for quantum engineering.Comment: 21 pages, 4 figures (preprint format

Anisotropic optical conductivity of the putative Kondo insulator CeRu4_4Sn6_6

Kondo insulators and in particular their non-cubic representatives have remained poorly understood. Here we report on the development of an anisotropic energy pseudogap in the tetragonal compound CeRu$_4$Sn$_6$ employing optical reflectivity measurements in broad frequency and temperature ranges, and local density approximation plus dynamical mean field theory calculations. The calculations provide evidence for a Kondo insulator-like response within the $a-a$ plane and a more metallic response along the c axis and qualitatively reproduce the experimental observations, helping to identify their origin

The Physiological Effects Of a Mid-shift feed of sucrose

When men work continuously at a moderate (1'0 litres/ min oxygen consumption) or hard rate (1'5 litres/ min oxygen consumption) for 6 hours, the respiratory quotient falls from 0·94 to 0·80. In classical concepts this ind:cates that 68% of the caloric requirement comes from carbohydrate initially and that only 30% comes from that source at the end of the work period. This change in metabolism is associated with an increase in oxygen consumption and heart rate, indicating that the men were being less effective mechanically towards the end of the work period when they were using predominantly fat metabolism. A mid-shift feed of 100 and of 200 g of sucrose in water .caused an immediate rise in RQ and a higher level of RQ than in the fasting men which persisted for the rest of the work period. This was associated with a lower rate of oxygen consumption than in the fasting state. Whife there may be some doubt about the immediate increase in RO being due to a shift towards carbohydrate metabolism after' the ingestion of sucrose, there can be little doubt that this is the case from the end of the first hour onwards, after the ingestion of sucrose. The doubt about whether the rapid increase in RQ after the ingestion of sucrose is due to a change from fat to carbohydrate metabolism or whether it is due to an alteration in blood insulin level following the ingestion of sucrose could be resolved by ingesting HC sucrose and studying the output of HC CO, in expired air. In view of the practical importance to industry of showing whether or not carbohydrate given during a mid-shift feed is actually metabo'ized during the remainder of the shift, a study with HC sucrose appears to be fully justified; its scientific value in solving the above problems is not in doubt

TINTE - A two-dimensional code for reactor dynamics

The TINTE main documentation consists of three parts, the first two of which/1/,/2/ have been published (in German) in the late eighties. In the first part the problems of modelling the nuclear and thermo-gas-dynamic behaviour of the primary circuit of a high temperature gas cooled reactor (HTGR) have been discussed in detail. It has been explained how the multiconnected system can be decomposed into single tasks to be solved separately. The solution of the total system is thus found by iteration of the partial results. In the second part of the documentation some major applications of TINTE are demonstrated. Among them the analyses of dynamic reactor experiments performed at the AVR reactor /4/ are of special interest. These results play a major role in the TINTE validation process, and the very good conformance obtained with the experimental data validate the TINTE calculations to a considerable extent. Earlier post-calculations of the AVR experiments with a previous version of the TINTE code have been described in /5/. Moreover, the basic algorithms as used in TINTE together with some applications have been shown in /4/. Since not all of the capabilities of TINTE could be addressed in these analysis, the validation process was continued, e.g. with the evaluation of the VELUNA corrosion experiments /6/. An addendum to the principal considerations of /1/ has been added as a supplement to /2/. Here the gas flow in an optional 1-D component and flow network is described, which may be used to enhance the 2-D reactor model for special situations. This flow network was necessary to model non-central pipes and other three-dimensional gas flow paths. It allows the description of co-axial pipes and a lumped parameter simulation of the primary side ofheat exchangers or steam generators. One example in /4/ shows that under certain limitations even a simulation of a gas-gas heat exchanger and the incorporation of the secondary loop is possible with the aid of that flow-network. In this addendum the possibility is also introduced to calculate the pressure inside the reactorfrom a given (fixed or variable in time) gas inventory. This is of relevance for accident analyses, where a failure of the pressure enclosure is assumed. If the pressure increases significantly gas may be removed from the system by burst discs or safety valves. This document starts with a description of the TINTE code structure (Section 4), while Section 5 is dedicated to the description and interpretation of the main input data. Section 6 deals with the preparation of the nuclear data base, the generation of the cross-section polynomial expansions and the necessary interface codes. Aspects included here are the evaluation of nuclide vectors (prepared by burn-up codes) and the preparation of spectrum calculations with variation of temperatures, buckling and concentrations for spectrum relevant nuclides. User notes on the code installation and calculational procedures are presented in Section 7, while Sections 8 and 9 discuss the TINTE control options and output data options, respectively. Section 10 lists the changes made in the TINTE source code over the years. The report also includes in the Appendices some newer algorithms for the treatment of special situations, while a description of the correlations used for the heat capacities and thermal conductivities are also given. Of special note here is Appendix E, which lists the detail of the ROMO model newly implemented in TINTE in 2004

Psychiatric morbidity in prisoners with intellectual disabilities: analysis of prison survey data for England and Wales

A substantial number of prisoners have intellectual disabilities. We analysed data on a sample drawn from all prisons in England and Wales. Intellectual disability was defined as Quick Test scores equivalent to an IQ of <= 65. We found a significantly higher prevalence of probable psychosis, attempted suicide and cannabis use in prisoners with intellectual disabilities. Presence of intellectual disability was twice as likely to be associated with probable psychosis but the relationship was fully mediated by self-rated health status. It is important to identify this group as early as possible in order to provide timely interventions to cope in adverse environments and manage substance misuse