135 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
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
Phase III randomized trial comparing moderate-dose cisplatin to combined cisplatin and carboplatin in addition to mitomycin and ifosfamide in patients with stage IV non-small-cell lung cancer
A phase III randomized trial was conducted in patients with metastatic NSCLC, to determine if, in association with mitomycin (6 mg m–2) and ifosfamide (3 g m–2), the combination of moderate dosages of cisplatin (60 mg m–2) and carboplatin (200 mg m–2) – CarboMIP regimen – improved survival in comparison with cisplatin (50 mg m–2) alone – MIP regimen. A total of 305 patients with no prior chemotherapy were randomized, including 297 patients assessable for survival (147 in the MIP arm and 150 in the CarboMIP arm) and 268 patients assessable for response to chemotherapy. All but eight (with malignant pleural effusion) had stage IV disease. There was a 27% (95% CI, 19–34) objective response (OR) rate to MIP (25% of the eligible patients) and a 33% (95% CI, 24–41) OR rate to CarboMIP (29% of the eligible patients). This difference was not statistically significant (P = 0.34). Duration of response was not significantly different between both arms. There was also no difference (P = 0.67) in survival: median survival times were 28 weeks (95% Cl, 24–32) for MIP and 32 weeks (95% Cl, 26–35) for CarboMIP, with respectively 1-year survival rates of 24% and 23% and 2-year survival rates of 5% and 2%. The main toxicities consisted in emesis, alopecia, leucopenia and thrombocytopenia, that were, except alopecia, significantly more severe in the CarboMIP arm. Our trial failed to demonstrate a significant improvement in response or survival when patients with metastatic NSCLC were treated, in addition to ifosfamide and mitomycin, by combination of moderate dosages of cisplatin and carboplatin instead of moderate dosage of cisplatin alone. The results support the use of a moderate dose (50 mg m–2) of cisplatin in combination with ifosfamide and mitomycin for the chemotherapy of this disease. © 2000 Cancer Research Campaig
Kondo screening of the spin and orbital magnetic moments of Fe impurities in Cu
We use x-ray magnetic circular dichroism to evidence the effect of correlations on the local impurity magnetic moment in an archetypal Kondo system, namely, a dilute Cu:Fe alloy. Applying the sum rules on the Fe L2,3 absorption edges, the evolution of the spin and orbital moments across the Kondo temperature are determined separately. The spin moment presents a crossover from a nearly temperature-independent regime below the Kondo temperature to a paramagneticlike regime above. Conversely, the weak orbital moment shows a temperature-independent behavior in the whole temperature range, suggesting different Kondo screening temperature scales for the spin and orbital moments
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