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Colossal magnetoresistance
About: Colossal magnetoresistance is a research topic. Over the lifetime, 3658 publications have been published within this topic receiving 130104 citations.
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32 citations
TL;DR: In this paper, the authors investigated magnetotransport properties for Sm1−xSrxMnO3 films that were prepared by the pulsed laser deposition technique and showed that the magnetoresistance shows an irreversible behavior against the magnetic field sweep.
Abstract: Magnetotransport properties were investigated for Sm1−xSrxMnO3 films that were prepared by the pulsed laser deposition technique. Application of a magnetic field causes a huge change in the resistivity for x=0.45, 0.50, and 0.55, in some cases exceeding five orders of magnitude. Measurement of the magnetization curve at low temperature which is removed after loading of a high magnetic field (5T) suggests the existence of the antiferromagnetic correlations. In accord with this, the magnetoresistance shows an irreversible behavior against the field sweep. The results imply that the colossal isothermal magnetoresistance in the thin films, of which the hole concentration is of a commensurate value of around x=1/2, has the same origin as the magnetic‐field‐induced first‐order transition reported for the single crystals that is the magnetic‐field‐induced melting of the charge‐ordered state.
32 citations
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TL;DR: In this paper, the authors studied the spin excitation spectrum in the double exchange model in the presence of disorder and found that at the zone center, the linewidth has a $q$ linear component while the excitation energy scales to $q^2, indicating that the magnon excitation is incoherent.
Abstract: Spin excitation spectrum is studied in the double exchange model in the presence of disorder. Spin wave approximation is applied in the lowest order of 1/S expansion. The disorder causes anomalies in the spin excitation spectrum such as broadening, branching, anticrossing with gap opening. The origin of the anomalies is the Friedel oscillation, in which the perfectly polarized electrons form the charge density wave to screen the disorder effect. Near the zone center $q = 0$, the linewidth has a $q$ linear component while the excitation energy scales to $q^2$, which indicates that the magnon excitation is incoherent. As $q$ increases, there appears a crossover from this incoherent behavior to the marginally coherent one in which both the linewidth and the excitation energy are proportional to $q^2$. The results are compared with experimental results in colossal magnetoresistance manganese oxides. Quantitative comparison of the linewidth suggests that spatially-correlated or mesoscopic-scale disorder is more relevant in real compounds than local or atomic-scale disorder. Comparison with other theoretical proposals is also discussed. Experimental tests are proposed for the relevance of disorder.
32 citations
TL;DR: It is concluded that such nanostructure-based studies have strong potential to reveal new information about the rich physics at work in strongly correlated materials, particularly in transition metal oxides, manganites, and high temperature cuprate superconductors.
Abstract: Strongly correlated materials exhibit an amazing variety of phenomena, including metal-insulator transitions, colossal magnetoresistance, and high temperature superconductivity, as strong electron-electron and electron–phonon couplings lead to competing correlated ground states. Recently, researchers have begun to apply nanostructure-based techniques to this class of materials, examining electronic transport properties on previously inaccessible length scales, and applying perturbations to drive systems out of equilibrium. We review progress in this area, particularly emphasizing work in transition metal oxides (Fe3O4, VO2), manganites, and high temperature cuprate superconductors. We conclude that such nanostructure-based studies have strong potential to reveal new information about the rich physics at work in these materials.
32 citations
TL;DR: In this article, the magnetoresistance of the La0.67Ca0.33MnO3−δ thin films was investigated and it was shown that the resistivity depends on ablation conditions such as substrate temperature and oxygen pressure and has a relation with the lattice constants of the thin films.
Abstract: Magnetoresistance of the La0.67Ca0.33MnO3−δ thin films was investigated. The magnetoresistance depends on ablation conditions such as the substrate temperature and oxygen pressure and has a relation with the lattice constants of the thin films. A colossal magnetoresistance ratio with 4.79×106% was obtained at 70 K and a magnetic field of 5.5 T. The resistivity of the thin films has a close relation with the substrate temperature and the oxygen pressure. When the substrate temperature is fixed, the resistivity shows double peaks in the oxygen pressure range of 1×10−7 to 1 Torr.
32 citations