Fabrication and characterization of SmCo5/Nb ferromagnetic/superconducting hybrid thin films grown by RF magnetron sputtering technique

Ferromagnet/Superconductor (F/S) bilayer hybrids show exclusive states due to the mutual interaction between the superconductor and the underlying ferromagnetic substructures in micron scale. In this work, we aimed to observe the effects of the interaction between superconductivity and magnetism, especially the phenomenon involving the orientation and the size of magnetic stripes has been investigated in a coupled ferromagnetic/superconducting thin-film structure. In the proposed F/S hybrid system by this work, superconducting niobium thin-films were combined with underlying segments of ferromagnetic SmCo5 substructures. 300 nm thick magnetic films fabricated by RF magnetron sputtering techniques were topographically grown in patterns with stripes oriented either transverse to or along the direction of current flow. The elemental and microstructural analyses were conducted by EDX, SEM and GIXRD characterization tools. Low-temperature DC transport measurements were conducted by means of four point probe method in a 9T closed-cycle cryogenic refrigeration system. Transport superconducting properties, transition temperature TC(H) and second critical field HC2(T) were measured in a range of applied magnetic field between H = 0–9 kOe for the hybrid system. The results revealed that the artificial periodic modulation of applied field through preferentially-oriented magnetic stripes could introduce normal and superconducting channels or barriers for the current flow. © 2017 Elsevier Lt

Sedimentological and geochemical characteristics of a fluvial travertine: A case from the eastern mediterranean region

A sedimentological and geochemical study was performed on the travertines in the southern part of the Uşak geothermal field, western Turkey, to assess the applicability of a fluvial tufa facies model in interpreting late Quaternary travertine deposits developed along the stream valleys that follow fault and fracture systems. Modern thermal (31 to 38°C) springs are found on the floor of the valley between 480 m and 520 m above sea-level. The distribution and nature of travertine facies were determined from natural outcrops. Samples of the travertines and spring water were characterized using a range of geochemical and petrographic methods. Waterfall, slope and pool facies associations consist of various combinations of travertine facies and subordinate detrital facies. Waterfall and slope facies associations of the older deposits occur where the springs emerged onto a hillslope or topographic break. In contrast, the pool facies association developed in depressions or flat areas that were fed by thermal springs. The youngest generation (1·85 ka) precipitated at lower elevations than the older ones (147 to 153 ka). Stable carbon and oxygen isotope values of the Aksaz travertines range between +4·3‰ and +6·3‰ (Vienna Pee Dee Belemnite) and -12·6‰ and -7·2‰ (Vienna Pee Dee Belemnite), respectively. The high δ13C values suggest that the thermal waters were charged with isotopically heavy CO2 of deep origin. Based on palaeotemperature calculations, the temperatures of the palaeosprings are slightly higher (up to 44°C) than the present equivalents, but sometimes the temperature is lower, probably due to mixing with the stream water. Although the thermal waters occasionally are impeded by fluvial activity, travertine precipitation occurs in the protected parts of the Aksaz Stream valley. This contribution highlights the applicability of the fluvial facies model for tufa for the interpretation of travertine deposits worldwide. © 2013 International Association of Sedimentologists

On Nonlinear Set-Valued θ\theta θ-Contractions

WOS: 000526822700023In this paper, we introduce and study new fixed point results for nonlinear set-valued theta-contractions. Our results are based on a new approach, which is called set-valued theta-contraction and they extend and generalize many fixed point theorems in the literature