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arXiv 2607.00526cond-mat.mtrl-sci
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颗粒各向异性对纳米颗粒复合材料中“双量子”磁共振激发的影响

Effect of granules anisotropy on "double quantum" magnetic resonance excitation in nanogranular composites

P.L.Kapitza Institute for Physical Problems, RAS（俄罗斯科学院普列奥布拉任斯基物理问题研究所）；Voronezh State Technical University（沃罗涅日国立技术大学）；National Research Centre Kurchatov Institute（库尔恰托夫国家研究中心）；Institute of Theoretical and Applied Electrodynamics, RAS（俄罗斯科学院理论与应用电动力学研究所）；Kotelnikov Institute of Radio Engineering and Electronics, Fryazino Branch, RAS（俄罗斯科学院科捷利尼科夫无线电工程与电子学研究所弗拉基诺分部）

A. B. Drovosekov, M. Yu. Dmitrieva, A. V. Sitnikov, S. N. Nikolaev, V. V. Rylkov

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AI总结：

通过电子自旋共振研究(CoFeB)x(Al2O3)100-x薄膜，发现双有效g因子~4的额外吸收峰，解释为铁磁颗粒中的“双量子”跃迁，并研究了浓度和退火对峰强的影响，证实了颗粒尺寸与各向异性的关联。

摘要：

采用电子自旋共振（ESR）方法，在宽频率（f = 7-80 GHz）和温度（T = 4.2-300 K）范围内，研究了不同金属铁磁（FM）相CoFeB含量（x ~ 15-50 at.%）的金属-绝缘体纳米颗粒复合材料(CoFeB)x(Al2O3)100-x薄膜。除了常规的FM共振信号外，实验谱图还显示了一个额外的吸收峰，其有效g因子为g ~ 4，这用量子力学“巨自旋”模型解释为FM颗粒CoFeB中“双量子”跃迁的激发。根据理论，该“双量子”峰的强度是频率和温度的复杂函数，包括颗粒磁矩和各向异性作为参数。实验中，颗粒的尺寸和各向异性可以通过改变复合材料中名义FM相含量x或在不同温度下退火样品来改变。这里我们研究了浓度x和热退火对(CoFeB)x(Al2O3)100-x薄膜ESR谱参数的影响。观察到的“双量子”峰强度行为在所考虑的“巨自旋”理论概念内得到了很好的解释。最后，我们展示了纳米复合材料中FM颗粒尺寸与其各向异性之间的相关性，表明这种各向异性的表面起源。

英文摘要：

Films of metal-insulator nanogranular composites (CoFeB)x(Al2O3)100-x with different contents of the metal ferromagnetic (FM) phase CoFeB (x ~ 15-50 at.%) are investigated by the method of electron spin resonance (ESR) in a wide range of frequencies (f = 7-80 GHz) and temperatures (T = 4.2-300 K). Besides the conventional FM resonance signal, the experimental spectra demonstrate an additional absorption peak with a double effective g-factor g ~ 4 which is explained within the quantum mechanical "giant spin" model by excitation of "double quantum" transitions in FM granules CoFeB. According to the theory, the intensity of this "double quantum" peak is a complex function of frequency and temperature, including as parameters the granule magnetic moment and anisotropy. Experimentally, the size and anisotropy of the granules can be varied either changing the nominal FM phase content x in the composites or annealing the samples at different temperatures. Here we study the effects of concentration x and thermal annealing of (CoFeB)x(Al2O3)100-x films on their ESR spectral parameters. The observed behavior of the "double quantum" peak intensity is well explained within the considered "giant spin" theoretical concept. In conclusion, we demonstrate the correlation between the size of FM granules in nanocomposites and their anisotropy, indicating the surface origin of this anisotropy.

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。

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