2,479 research outputs found
Study of Ni and Zn doped CeOFeAs: Effect on the structural transition and specific heat capacity
We have systematically studied the substitution of nonmagnetic Zn and
magnetic Ni at iron sites in Ce based oxypnictide. The parent compound
(CeOFeAs) shows an anomaly in resistivity around 150 K due to structural
transition from tetragonal (space group: P4/nmm) to orthorhombic structure
(space group: Cmma). Substitution of Zn suppresses this anomaly to lower
temperature (~130 K) but Ni substitution does not show any anomaly around this
temperature and the compound behaves like a metal. Further, we find that non
magnetic (Zn) doping leads to higher impurity scattering as compared to
magnetic Ni doping. Similar to the resistivity measurement, the specific heat
shows another jump near 4 K for CeOFeAs. This is attributed to the ordering of
Ce3+ moments. This peak shifts to 3.8 K for Zn substituted compound and there
is no change in the ordering temperature in the Ni substituted CeOFeAs. These
peaks are broadened in applied magnetic field (5 T) and the calculated magnetic
entropy tends to saturate at the same value for 0 T and 5 T external magnetic
field.Comment: 16 pages Text+Fig
Superconductivity at 11.3 K induced by cobalt doping in CeOFeAs
Pure phases of a new oxyarsenide superconductor of the nominal composition
CeOFe0.9Co0.1As was successfully synthesized by solid state reaction in sealed
silica ampoules at 1180 C. It crystallizes in the layered tetragonal ZrCuSiAs
type structure (sp gp P4/nmm) with lattice parameter of a = 3.9918(5) angstrom
and c = 8.603(1) angstrom. A sharp superconducting transition is observed at
11.31 K with an upper critical field of 45.22 T at ambient pressure. The
superconducting transition temperature is drastically lowered (~ 4.5, 4.9 K) on
increasing the concentration (x = 0.15, 0.2) of cobalt
Upper critical field, superconducting energy gaps, and Seebeck coefficient in La0.8Th0.2OFeAs
We report the synthesis and characterization of a new electron-doped
La-oxypnictide superconductor by partial substitution of lanthanum by thorium.
The superconducting transition temperature at about 30.3 K was observed in
La0.8Th0.2OFeAs which is the highest in La-based oxypnictide superconductors
synthesized at ambient pressure. We find that the decrease in lattice
parameters with Th doping in LaOFeAs is more drastic as compared to that
obtained by high pressure (6 GPa) synthesis of oxygen deficient LaOFeAs. The
resistivity and magnetic susceptibility measurements yield an upper critical
field Hc2 (0) of 47 T. Partial substitution of Th in place of La induces
electron doping as evidenced by negative Seebeck coefficient. The temperature
dependent magnetic penetration depth data provides strong evidence for a
nodeless low energy gap of 1.4 meV
Effect of Muons on the Phase Transition in Magnetised Proto-Neutron Star Matter
We study the effect of inclusion of muons and the muon neutrinos on the phase
transition from nuclear to quark matter in a magnetised proto-neutron star and
compare our results with those obtained by us without the muons. We find that
the inclusion of muons changes slightly the nuclear density at which transition
occurs.However the dependence of this transition density on various chemical
potentials, temperature and the magnetic field remains quantitatively the same.Comment: LaTex2e file with four postscript figure
Accessing adolescent friendly health clinics in India: The perspectives of adolescents and youth
The recently launched Rashtriya Kishor Swasthya Karyakram (RKSK) health program seeks to enable all adolescents and youth to realize their full potential by making informed and responsible decisions concerning their health and well-being and by accessing the services and support needed to implement their decisions. To realize this vision, the RKSK framework acknowledges that the strengthening of Adolescent Friendly Health Clinics (AFHCs) and the provision of correct knowledge and information through counseling services are two of its seven critical components. As the government makes efforts to roll out the RKSK program at scale across the country, reviewing the experiences of the AFHCs established under the National Adolescent Reproductive and Sexual Health Strategy (the predecessor of RKSK) can provide useful lessons. With this in view, at the request of the Ministry of Health and Family Welfare, the Population Council conducted an assessment of AFHCs from the perspectives of adolescents and youth, and health care providers in three states in India. This report presents the findings of the assessment conducted among adolescents and youth
Enhancement in transition temperature and critical current density of CeO<SUB>0.8</SUB>F<SUB>0.2</SUB>FeAs by yttrium doping
We report significant enhancement in superconducting properties of yttrium substituted Ce1-xYxOFFeAs superconductors. The polycrystalline samples were prepared by two step solid state reaction technique. X-ray diffraction confirmed tetragonal ZrCuSiAs structure with decrease in both a and c lattice parameters on increasing yttrium substitution (with fixed F content). With smaller ion Y in place of Ce, the transition temperature increased by 6 K. Yttrium doping also lead to higher critical fields as well as stronger inter and intra-granular current density. The magnetization critical current density increased by an order of magnitude at 30 K and 1 T magnetic field
Enhancement in transition temperature and critical current density of CeO0.8F0.2FeAs by yttrium doping
We report significant enhancement in superconducting properties of yttrium
substituted Ce1-xYxOFFeAs superconductors. The polycrystalline samples were
prepared by two step solid state reaction technique. X-ray diffraction
confirmed tetragonal ZrCuSiAs structure with decrease in both a and c lattice
parameters on increasing yttrium substitution (with fixed F content). With
smaller ion Y in place of Ce, the transition temperature increased by 6 K.
Yttrium doping also lead to higher critical fields as well as stronger inter
and intra-granular current density. The magnetization critical current density
increased by an order of magnitude at 30 K and 1 T magnetic field.Comment: 14 pages, 4 figure
Designing Mamdani-Type Fuzzy Reasoning for Visualizing Prediction Problems Based on Collaborative Fuzzy Clustering
In this paper a collaborative fuzzy c-means (CFCM) is used to generate fuzzy rules for fuzzy inference systems to evaluate the time series model. CFCM helps system to integrate two or more different datasets having similar features which are collected at the different environment with the different time period and it integrates these datasets together in order to visualize some common patterns among the datasets. In order to do any mode of integration between datasets, there is a necessity to define the common features between datasets by using some kind of collaborative process and also need to preserve the privacy and security at higher levels. This collaboration process gives a common structure between datasets which helps to define an appropriate number of rules for structural learning and also improve the accuracy of the system modeling
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