Topic
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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TL;DR: Polarized Raman scattering by phonons is used to characterize thin films prepared by laser ablation of La1−xCaxMnO3 targets in this article, where the observed Raman peaks and their linewidths exhibit an irregular temperature dependence near Tc.
Abstract: Polarized Raman scattering by phonons is used to characterize thin films prepared by laser ablation of La1−xCaxMnO3 targets. It was found that, in the temperature range from 6 to 300 K, phonon spectra of La0.7Ca0.3MnO3 films exhibit observable differences from those in bulk materials (microcrystalline ceramics and single crystals). A significant difference was found in the spectra of “as-grown” films compared to those annealed in oxygen at 800 °C. The observed Raman peaks and their linewidths exhibit an irregular temperature dependence near Tc. A correlation of Raman data with magnetization of the sample was also found.
45 citations
TL;DR: It is shown that ultrabroadband terahertz pulses can simultaneously trace the ultrafast evolution of coexisting lattice and electronic orders and demonstrates the sort of profound insight that disentangling strongly coupled components of order parameters in the time domain may provide for the understanding of a broad class of phase transitions.
Abstract: The simultaneous ordering of different degrees of freedom in complex materials undergoing spontaneous symmetry-breaking transitions often involves intricate couplings that have remained elusive in phenomena as wide ranging as stripe formation, unconventional superconductivity or colossal magnetoresistance. Ultrafast optical, x-ray and electron pulses can elucidate the microscopic interplay between these orders by probing the electronic and lattice dynamics separately, but a simultaneous direct observation of multiple orders on the femtosecond scale has been challenging. Here we show that ultrabroadband terahertz pulses can simultaneously trace the ultrafast evolution of coexisting lattice and electronic orders. For the example of a charge-density-wave (CDW) in 1T-TiSe2, we demonstrate that two components of the CDW order parameter - excitonic correlations and a periodic lattice distortion (PLD) - respond very differently to 12-fs optical excitation. Even when the excitonic order of the CDW is quenched, the PLD can persist in a coherently excited state. This observation proves that excitonic correlations are not the sole driving force of the CDW transition in 1T-TiSe2, and exemplifies the sort of profound insight that disentangling strongly coupled components of order parameters in the time domain may provide for the understanding of a broad class of phase transitions.
45 citations
TL;DR: In this paper, magnetization and electron-spin-resonance (ESR) measurements around the Curie temperature on single-crystal and ceramic colossal magnetoresistance manganites were reported.
Abstract: We report magnetization and electron-spin-resonance (ESR) measurements around the Curie temperature on single-crystal and ceramic colossal magnetoresistance manganites. The temperature dependence of the ESR linewidth below $\ensuremath{\approx}{1.1T}_{C}$ is well described in terms of a two-magnon scattering relaxation mechanism induced by the demagnetization fields of the pores between crystallites.
45 citations
TL;DR: In this paper, it was shown empirically that the saturation observed in the magnetoresistance is best fit by a simple resistor in series with a magnetoconductor: ρ(H)=ρ∞+1/(σ 0+γ|H|) for T TC.
Abstract: The observed H2 and |H| dependence of the magnetoresistance above and below TC, respectively, may be explained by general time‐reversal symmetry considerations. We further find empirically that the saturation observed in the magnetoresistance is best fit by a simple resistor in series with a magnetoconductor: ρ(H)=ρ∞+1/(σ0+γ|H|) for T TC. This provides a functional form to analyze and predict the magnetoresistance over a wide range of fields. This suggests that the underlying mechanism of ‘‘colossal magnetoresistance ’’ may be magnetoconductive, not magnetoresistive. The magnetoresistance and Hall effects on an annealed epitaxial thin films of La0.67Ca0.33MnO3 were measured at 0.9 TC and 1.1 TC. At low fields, anisotropic magnetoresistance plays a dominant role. The high field Hall effect shows holelike carriers above and below TC. The apparent change in sign at low fields is likely due to the anomalous Hall effect.
45 citations
TL;DR: This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form.
Abstract: Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Huang, Y.H.; Yamauchi, H.; Karppinen, Maarit
45 citations