161 research outputs found
Annealing effect on the structural, magnetic and transport properties in the CoxCu1-x granular alloys with 0.20 ≤ x ≤ 0.25 prepared by the ion-beam sputtering technique
We have studied the transport and magnetic properties of a metallic granular CoxCu1-x system, with 0.2≤x≤0.25, prepared by using an ion-beam sputtering technique. Giant magnetoresistance (GMR) has been observed for the all studied concentration with the average amplitude around 2%. at 300K. The maximum value has been observed for Co21Cu79 granular alloy after annealing at 450°C for 2h. Above this concentration the MR decreases which is attributed to the percolation effect, which causes a concurrent reduction in magnetic coercivity. The variation of magnetic and transport properties with the concentration and annealing time is discussed.We have studied the transport and magnetic properties of a metallic granular CoxCu1-x system, with 0.2≤x≤0.25, prepared by using an ion-beam sputtering technique. Giant magnetoresistance (GMR) has been observed for the all studied concentration with the average amplitude around 2%. at 300K. The maximum value has been observed for Co21Cu79 granular alloy after annealing at 450°C for 2h. Above this concentration the MR decreases which is attributed to the percolation effect, which causes a concurrent reduction in magnetic coercivity. The variation of magnetic and transport properties with the concentration and annealing time is discussed
Study of molecular spin-crossover complex Fe(phen)2(NCS)2 thin films
We report on the growth by evaporation under high vacuum of high-quality thin
films of Fe(phen)2(NCS)2 (phen=1,10-phenanthroline) that maintain the expected
electronic structure down to a thickness of 10 nm and that exhibit a
temperature-driven spin transition. We have investigated the current-voltage
characteristics of a device based on such films. From the space charge-limited
current regime, we deduce a mobility of 6.5x10-6 cm2/V?s that is similar to the
low-range mobility measured on the widely studied
tris(8-hydroxyquinoline)aluminium organic semiconductor. This work paves the
way for multifunctional molecular devices based on spin-crossover complexes
Control of defect-mediated tunneling barrier heights in ultrathin MgO films
The impact of oxygen vacancies on local tunneling properties across
rf-sputtered MgO thin films was investigated by optical absorption spectroscopy
and conducting atomic force microscopy. Adding O to the Ar plasma during
MgO growth alters the oxygen defect populations, leading to improved local
tunneling characteristics such as a lower density of current hotspots and a
lower tunnel current amplitude. We discuss a defect-based potential landscape
across ultrathin MgO barriers.Comment: 4 pages, 4 figure
Tri-critical point and suppression of the Shastry-Sutherland phase in CePdSn by Ni doping
Structural, magnetization and heat capacity measurements were performed on
Ce(PdNi)Sn () alloys, covering the full
range of the MoFeB structure stability. In this system, the two
transitions observed in CePdSn (at \,K and \,K
respectively) converge into a tri-critical point at \,K for
, where the intermediate antiferromagnetic AF phase is
suppressed. The phase boundary decrease is due to an incipient Kondo
screening of the Ce-4f moments and local atomic disorder in the alloy. Both
mechanisms affect the formation of Ce-magnetic dimers on which the
Shastry-Sutherland lattice (SSL) builds up. On the contrary, the
transition to the ferromagnetic ground state increases as a consequence of the
weakening of the AF-SSL phase. Applied magnetic field also suppresses the AF
phase like in the stoichiometric compound.Comment: 6 pages, 8 figure
Morphological and micro-structural interface characterization in multilayer inverted polymer-fullerene bulk heterojunction solar cells
Inverted polymer solar cells based on P3HT/PCBM bulk heterojunction were prepared on flexible polyethylene naphthalate (PEN) substrate. The effect of annealing of the PEN/ITO/ZnO multilayer and ZnO/P3HT:PCBM on the structural, morphological, photophysical and photovoltaic properties was investigated and scrutinized directly on the OPV devices using atom probe tomography (APT), scanning electron microscopy (SEM) and microfocus X-ray techniques. We carried out a 3D reconstruction of the interfaces of the multilayer containing PEN/ITO, ZnO/ITO and P3HT:PCBM/ZnO to address the interface micro-structure and its influence on the morphology of the photoactive film. The analyses show that the morphology of the interfaces is affected by the structure of each layer of the BHJ devices causing orientation of P3HT crystals with PCBM aggregates and ZnO, which in turn leads to a significant change of the charge transport across each layer and therefore photovoltaic performances
Stuctural And Magnetic Characterization Of CoxZn1-x/Cu Multilayers Obtained by Electrodeposition
We present the experimental results of (CoxZn1-x/Cu)n multilayers (3<x<10) grown using the electrochemical dual bath method. The X-ray diffraction patterns have shown that the CoZn structural lattice parameters are close to those of the monoclinic CoZn13 compound. We have developed an analytical model in the X-ray kinematical theory adapted to the electrodeposited (CoxZn1-x/Cu) multilayers. We have shown that the model can give interesting structural information about the multilayer components, and reproduces the position of the satellite peaks around the main diffraction peak. Thus we have deduced the multilayer period and performed comparison between experimental results and the analytical model. The magnetic properties at room temperature reveal both superparamagnetic and ferromagnetic features. The inclusion of Zn into the magnetic layer and the existence of CoZnCu based alloy at the interfacial regions explain the magnetic properties. The magnetoresistance (MR) loop displays a broad , rounded maximum and the saturation is not observed even at high applied fields. The MR(H) behaviour and its small ratio can be attributed to interfacial effects.We present the experimental results of (CoxZn1-x/Cu)n multilayers (3<x<10) grown using the electrochemical dual bath method. The X-ray diffraction patterns have shown that the CoZn structural lattice parameters are close to those of the monoclinic CoZn13 compound. We have developed an analytical model in the X-ray kinematical theory adapted to the electrodeposited (CoxZn1-x/Cu) multilayers. We have shown that the model can give interesting structural information about the multilayer components, and reproduces the position of the satellite peaks around the main diffraction peak. Thus we have deduced the multilayer period and performed comparison between experimental results and the analytical model. The magnetic properties at room temperature reveal both superparamagnetic and ferromagnetic features. The inclusion of Zn into the magnetic layer and the existence of CoZnCu based alloy at the interfacial regions explain the magnetic properties. The magnetoresistance (MR) loop displays a broad , rounded maximum and the saturation is not observed even at high applied fields. The MR(H) behaviour and its small ratio can be attributed to interfacial effects
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