The considerable spin diffusion length and high electron mobility of graphene at room temperature makes it a suitable candidate to improve the spin transport properties of magnetic semiconductors when incorporated in a suitable stoichiometry. Herein, an observation of room-temperature magnetoresistance (MR) properties of reduced graphene oxide (rGO)/cobalt ferrite (CFO) nanocomposites, which are synthesized by chemical methods followed by mixing in different mass ratios, is reported. The magnetic field-dependent electrical resistivity shows a decrease in resistivity with the increase in magnetic field from 0 to 0.5 T, representing a negative MR in our samples. The highest MR of around −1.4% is observed in the 1:1 ratio CFO and rGO nanocomposite, whereas the samples with 2:1 and 3:1 ratio show the MR of ≈−1%. In the CFO–rGO nanocomposite, the charge transport takes place mainly through the rGO layers due to the insulating nature of the CFO nanoparticles. However, the ferromagnetic moments of the CFO nanoparticles induce electron-spin scattering during the charge transport. The reduction in electron-spin scattering results due to the parallel alignment of the magnetic moments. The alignment of ferromagnetic moments under the external magnetic field has been further confirmed from the magnetocapacitance effect of CFO nanoparticles.

中文翻译：

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还原氧化石墨烯/CoFe2O4 纳米复合材料中室温低场磁阻的观察

石墨烯在室温下具有相当大的自旋扩散长度和高电子迁移率，当以合适的化学计量加入时，使其成为改善磁性半导体自旋输运特性的合适候选者。在此，报告了对还原氧化石墨烯 (rGO)/钴铁氧体 (CFO) 纳米复合材料的室温磁阻 (MR) 特性的观察，这些复合材料通过化学方法合成，然后以不同的质量比混合。与磁场相关的电阻率显示电阻率随着磁场从 0 T 增加到 0.5 T 而降低，代表我们样品中的负 MR。在 1:1 比率的 CFO 和 rGO 纳米复合材料中观察到大约 -1.4% 的最高 MR，而具有 2:1 和 3:1 比率的样品显示 MR ≈-1%。在 CFO-rGO 纳米复合材料中，由于 CFO 纳米粒子的绝缘特性，电荷传输主要通过 rGO 层进行。然而，CFO 纳米粒子的铁磁矩在电荷传输过程中会引起电子自旋散射。由于磁矩的平行排列，导致电子自旋散射的减少。CFO纳米粒子的磁电容效应进一步证实了外磁场下铁磁矩的排列。