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: In this paper, a theory of bound magnetic polaron (BMP) hopping, driven by thermodynamic fluctuations of the local magnetization, has been developed based on a two-site model of the BMP.
Abstract: A theory of bound magnetic polaron (BMP) hopping, driven by thermodynamic fluctuations of the local magnetization, has been developed. It is based on a two-site model of the BMP. The BMP hopping probability rate was calculated in the framework of the ``golden rule'' approach by using the Ginzburg-Landau effective Hamiltonian method. The theory explains the main features of the hopping resistivity observed in a variety of experiments in dilute magnetic semiconductors and magnetic nanocomposites, namely, (a) the negative giant magnetoresistance, the scale of which is governed by a magnetic polaron localization volume, and (b) the low-magnetic-field positive magnetoresistance which usually precedes the negative magnetoresistance. It is shown that the positive magnetoresistance is a signature of the fluctuation-driven bound magnetic polaron hopping. This effect is related to the vector nature of the magnetic order parameter affected by the presence of the localized-electron spin.
33 citations
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TL;DR: The magnetism and transport properties of the samples LaMn1−xTixO3 (0≤x≤0.2) were investigated in this article.
32 citations
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TL;DR: In this article, the exchange bias effect was observed in Nd2/3Ca1/3MnO3 colossal magnetoresistance perovskite below the Curie temperature of 70 K and attributed to an antiferromagnetic (AFM)-ferromagnetic 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 $T_{C}$ = 70 K and attributed to an antiferromagnetic (AFM) - 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 $H_{EB}$ and coercivity $H_{C}$ are found to be strongly dependent of temperature and strength of the cooling magnetic field $H_{cool}$. 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 $T_{C}$ 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
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TL;DR: In this paper, a spin-glass to ferromagnet transition in a modest applied magnetic field has been found in the single-valent perovskite system LaMn1−xScxO3 as in the analogous system LaN 1−xGaxO3, which supports the existence of a ferromagnetic vibronic-superexchange interaction between octahedral-site, high-spin Mn(III) with fluctuating e-orbitals.
32 citations
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TL;DR: In this article, the effects of Fe doping on the magnetic, transport, and magnetoresistance properties are studied for La0.7Sr0.88Fe0.12O3 oxides.
Abstract: The effects of Fe doping on the magnetic, transport, and magnetoresistance properties are studied for La0.7Sr0.3Mn1−yFeyO3 (y=0–0.18) and La1−xSrxMn0.88Fe0.12O3 (x=0.1–0.50). For increasing y, a peak in the thermal dependence of the resistivity appears and develops at the temperature TPl lower than TC, while the another peak near TC becomes smaller and then disappears. At 78 K the La1−xSrxMn0.88Fe0.12O3 oxides are insulators for x 0.5 and only the lower-temperature metal–insulator transition peak appears for 0.25
32 citations