Papers by Keyword: Magnetoresistivity MR

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Authors: Cheng Zhou, Tatsuhiko Aizawa, Kazuto Tokumitsu, Kiyohiko Tatsuzawa, Junji Kihara
Authors: Kundu Sourav, Kumar Nath Tapan
Abstract: We have reported in this paper, the effect of grain size in Nd0.6Sr0.4MnO3 .We have investigated the effect of grain size on metal-insulator transition and Curie temperature. We have also reported here the variation of low field magnetoresistance with temperature and grain size. We have observed that the Curie temperature increases monotonically with particle size. The metal insulator transition temperature initially increases with particle size and then gets fixed to a certain value. In these Nd0.6Sr0.4MnO3 nanometric systems, any significant variation of magnetoresistance with particle size is not observed.
Authors: Duncan M. McCann, Grant V. M. Williams, Adam R. Hyndman, Jibu Stephen
Abstract: We observe a large magneto-resistance in very thin Ba2FeMoO6 films of ~-12% at 10K, which is not significantly changed when thin NiFe/Ba2FeMoO6 bi-layers are made. This suggests that the magneto-resistance in both cases is dominated by inter-grain tunnelling in the Ba2FeMoO6 thin film. There is an anomalous peak in the resistance at ~300K in the bi-layer film that can not be easily explained. However, we know that the temperature where this peak occurs is close to the Ba2FeMoO6 Curie temperature.
Authors: A.S. Samardak, E.V. Sukovatitsina, A.V. Ognev, M. Anisimova, Erik Wahlström, L.A. Chebotkevich
Abstract: This paper is devoted to the investigation of crystalline structure, surface morphology, magnetic anisotropy, coercive force and domain structure of spin-valves with a single and double MgO barrier layers. It is shown that domain structure and magnetization reversal are the same for both systems, but otherwise the behavior of tunnel magnetoresistance is different. The approach to control magnetic anisotropy in soft magnetic layer using temperature annealing is demonstrated. It makes these structures possible for new applications in nanoelectronics.
Authors: Q.Z. Xue, X. Zhang
Abstract: Using pulsed laser deposition we prepared Fex-C1-x films on Si (100) substrates. We show that the lightly Fe-doped amorphous carbon films on Si substrate have large MR at room temperature. At T=300K and B=5T a large positive MR of 138% was found in Fe0.011-C0.989 film. Furthermore, we find that when temperature T<258K, the MR of Fe0.011-C0.989 film on Si substrate is negative and when 258K
Authors: Anatoly Ye. Yermakov, Mikhail A. Uimin, A.V. Shangurov, Alexander V. Zarubin, Y.V. Chechetkin, A.K. Shtolz, V.V. Kondratyev, G.N. Konygin, Y.P. Yelsukov, Stefano Enzo, P.P. Macrí, R. Frattini, Neil Cowlam
Authors: Jian Wu
Abstract: The transport properties of the inhomogeneous system (1/4) Ag2O-La0.833Na0.167MnO3 (LNMO/Ag) have been systematically studied. X-ray diffraction patterns show that the LNMO/Ag sample is the two-phase composite and consists of a magnetic La0.833Na0.167MnO3 (LNMO) perovskite phase and a nonmagnetic Ag metal phase. The resistivity of the sample decreases dramatically with Ag added into the pure perovskite LNMO manganites. For the LNMO/Ag sample, the Curie temperature TC is 331 ± 2 K and slightly higher than that of the LNMO sample (323 ± 2 K). Due to the dope of Ag metal, the room temperature magnetoresistance effect is enhanced significantly (from 7% for the pure LNMO manganites to 23% for the LNMO/Ag sample under a relative lower field of 0.5 T and from 37.5% for the LNMO sample to 41 % for the LNMO/Ag sample under a high field of 6 T at the temperature of 330 K. In the low temperature regime, the magnetoresistance ratio of the LNMO/Ag sample is smaller than that of the LNMO sample, which is contrary to the magnetoresistance effect in high temperature. The effects are discussed qualitatively by use of a model which is based on the relative change among the intrinsic magnetoresistance effect and the extrinsic magnetoresistance effect.
Authors: Bai Yang, Xiao Fang Bi, Fan Yang, Sheng Kai Gong, Hui Bin Xu
Abstract: NiFe(2nm)/Cu(tCu)/Co(1.5nm) sandwiches were deposited on Ta buffer layer by magnetron sputtering method. Small angle X-ray diffraction analysis was made to investigate the structural characterizations of the sandwiches. It has been obtained that MR value showed a maximum at tCu=2nm when Cu spacer thickness changed, which is contributed by the effect of shutting and interlayer coupling. The Cu layer was deposited at two different rates. Larger MR ratio was observed with a lower deposition rate. The result was discussed in terms of magnetic reversal fields. In addition, the sandwiches were subjected to field annealing at different annealing temperatures. MR ratio has exhibited a largest increase after annealing at 175oC with a magnetic field of 750Oe applied.
Authors: Shui Yuan Chen, Zhi Gao Huang, Heng Lai, Rongquan Gai, Feng Ming Zhang, You Wei Du
Abstract: Ferromagnetic (FM) La2/3(Ca0.6Ba0.4)1/3MnO3 and antiferromagnetic (AFM) NiO nanoparticles were synthesized using sol-gel method, respectively. La2/3(Ca0.6Ba0.4)1/3MnO3 (1 mol)/ x NiO (x= 0, 0.05 and 0.15mol) composites with the coated NiO were prepared. The experimental results indicate that, both phases of LCBMO and NiO coexist clearly in the composites and the sizes of the NiO nanoparticles in the intergranular region between the LCBMO particles are very small; the interface of NiO influences evidently the value of MR and it is found that the tunneling MR for x=0.05 is the largest in three samples. The magnetoresistance behavior has been explained by two-level model of tunneling magnetoresistance and percolation model well.
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