磁性纳米复合材料中 g $\approx$ 4 EPR 谱线的起源：铁磁颗粒中双量子跃迁的体现
The origin of g $\approx$ 4 EPR line in magnetic nanocomposites: Manifestation of double quantum transitions in ferromagnetic granules
AI总结：
本文利用电子磁共振技术研究金属-绝缘体纳米颗粒复合薄膜，发现低于渗流阈值时出现 g ≈ 4 的额外吸收峰，并用量子力学“巨自旋”模型将其归因于自旋投影变化 Δm = ±2 的“禁戒”双量子跃迁激发。
摘要：
本文利用电子磁共振技术，在宽频段（f = 7-37 GHz）和宽温度范围（T = 4.2-360 K）内，研究了具有不同成分及金属与介电相原子百分比的金属-绝缘体纳米颗粒复合薄膜 M$_x$D$_{100-x}$（M = Fe, Co, Ni, CoFeB；D = Al$_2$O$_3$, SiO$_2$, ZrO$_2$；x $\approx$ 15-60 at.%）。当金属铁磁相浓度低于渗流阈值时，实验谱图除了常规的铁磁共振信号外，还表现出一个以双有效 g 因子 g $\approx$ 4 为特征的额外吸收峰。在量子力学“巨自旋”模型框架下，该共振谱中此峰的出现及其反常特性，被解释为磁性纳米颗粒中自旋投影变化 $Δm = \pm2$ 的“禁戒”（“双量子”）跃迁激发所致。
英文摘要：
Films of metal-insulator nanogranular composites M$_x$D$_{100-x}$ with different compositions and atomic percentage of metal and dielectric phases (M = Fe, Co, Ni, CoFeB; D = Al$_2$O$_3$, SiO$_2$, ZrO$_2$; x $\approx$ 15-60 at.%) are investigated by electron magnetic resonance in a wide range of frequencies (f = 7-37 GHz) and temperatures (T = 4.2-360 K). At concentrations of the metallic ferromagnetic phase below the percolation threshold, the experimental spectra, besides the conventional ferromagnetic resonance signal, demonstrate an additional absorption peak characterized by a double effective g-factor g $\approx$ 4. The appearance of such a peak in the resonance spectra and its unusual properties are explained in the framework of the quantum mechanical "giant spin" model by the excitation of "forbidden" ("double quantum") transitions in magnetic nanogranules with a change of the spin projection $Δm = \pm2$.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
