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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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TL;DR: Results strongly suggest that chemical disorder lowers the energy for polaron formation in manganese perovskites, and is the origin of the dramatic 50 K reduction in TC.
Abstract: Neutron studies of the effect of A-site chemical disorder on the ferromagnetic transition and spin dynamics for the magnetoresistive perovskite La0.54Ba0.46MnO3 are reported. The low temperature spin waves reveal that disorder reduces exchange interactions by only 9%. The development of a quasielastic peak in the spectrum below TC and long-time relaxation of the order parameter indicate that the transition is discontinuous in the disordered sample, while it appears continuous for the ordered sample. These results strongly suggest that chemical disorder lowers the energy for polaron formation in manganese perovskites, and is the origin of the dramatic 50 K reduction in TC.

32 citations

Journal ArticleDOI
TL;DR: In this paper, a crystal field analysis of CMR manganites was proposed based on the assumption of a strong reduction, upon cooling, of the octahedral distortion due to the dynamic Jahn-Teller splitting present above.
Abstract: CMR manganites were studied by x-ray absorption spectroscopy at the O K-edge above and below the transition temperature . In compounds which keep the insulating behaviour in the whole temperature range, the prepeak at the O K-edge remains unique upon cooling even in the case of the presence of a paramagnetic-ferromagnetic transition. In compounds showing a spontaneous transition from a paramagnetic-insulating state to a ferromagnetic-metallic one, the prepeak at the O K-edge is split into two components. A crystal field analysis of this behaviour is proposed based on the assumption of a strong reduction, upon cooling, of the octahedral distortion due to the dynamic Jahn-Teller splitting present above . This reduction of the crystal field distortion at is correlated to the transition to the metallic state and to the presence of the magneto-resistant effect.

32 citations

Journal ArticleDOI
TL;DR: In this article, the 1/f noise enhancement at the metal-insulator transition was observed in La5/82yPryCa3/8MnO3 ( y50.320).
Abstract: We report studies of the 1/f noise in La5/82yPryCa3/8MnO3 ( y50.320.4) which exhibits the metal-insulator transition ~MIT! in zero magnetic field, and in Pr 12xCaxMnO3 (0.3,x,0.5), where the transition can be observed only in high magnetic field. Many-orders-of-magnitude noise enhancement at the MIT observed in both compounds indicates the generality of the percolation mechanism of the transition in these systems. Large discrete discontinuities of the resistivity—switching, which usually accompany the noise peak at the MIT— suggest that individual domains belonging to the percolation cluster undergo transitions back and forth between the metallic and insulating states. Signatures of metastability of the low temperature electronic state in these charge-ordered manganites and similarity of the switching dynamics with that of non-charge-ordered compounds indicate that the percolating phases in the studied systems are the ferromagnetic metallic and the metastable charge-disordered insulating phases.

32 citations

Journal ArticleDOI
TL;DR: In this paper, the exchange bias effect decreases with increasing temperature up to TC and vanishes above this temperature with disappearance of the antiferromagnetic-ferromagnetic (FM) spontaneous phase segregated state of this compound.
Abstract: Exchange bias (EB) phenomena have been observed in Nd2/3Ca1/3MnO3 colossal magnetoresistance perovskite below the Curie temperature TC ∼ 70 K and attributed to an antiferromagnetic–ferromagnetic (FM) spontaneous phase segregated state of this compound. Field cooled magnetic hysteresis loops exhibit shifts toward negative direction of the magnetic field axis. The values of exchange field HEB and coercivity HC are found to be strongly dependent of temperature and strength of the cooling magnetic field Hcool. These effects are attributed to evolution of the FM phase content and a size of FM clusters. A contribution to the total magnetization of the system due to the FM phase has been evaluated. The exchange bias effect decreases with increasing temperature up to TC and vanishes above this temperature with disappearance of FM phase. Relaxation of a non-equilibrium magnetic state of the compound manifests itself through a training effect also observed while studying EB in Nd2/3Ca1/3MnO3.

32 citations

Journal ArticleDOI
TL;DR: In this article, magnetotransport measurements on millimetric superlattices of Co-Fe nanoparticles surrounded by an organic layer were performed and it was shown that the transition between the Coulomb blockade and the conductive regime becomes abrupt and hysteretic.
Abstract: We report on magnetotransport measurements on millimetric superlattices of Co-Fe nanoparticles surrounded by an organic layer. At low temperature, the transition between the Coulomb blockade and the conductive regime becomes abrupt and hysteretic. The transition between both regimes can be induced by a magnetic field, leading to a novel mechanism of magnetoresistance. Between 1.8 and 10 K, a high-field magnetoresistance attributed to magnetic disorder at the surface of the particles is also observed. Below 1.8 K, this magnetoresistance abruptly collapses and a low-field magnetoresistance is observed.

32 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202330
202252
202139
202038
201937
201837