宽损耗频带纳米软磁薄膜的微波损耗机理研究

The nanometer-grade soft-magnetic films, with high permeability and wide absorb frequency band, possess the potential values for the application in the electromagnetic shielding and radar wave absorbing area. At present, the understanding of the damping mechanisms of the soft-magnetic films is not in-depth enough, and especially the research on the topic of broadening the damping frequency band just begins. Uniquely, this program will prepare some series of FeCo-based soft magnetic films which within the multiple magnetic phases, and the homogeneity of those films will be adjusted by controlling the technology of multiple target alternately sputtering and annealing. Because of the different microwave response of the magnetic grains with the different composition and size, multiple resonance peaks will become visible in their permeability spectra, which could broaden the damping frequency band and keeps the high permeability at the same time. We will study the influence of the grains' composition, size, homogeneity and the medium, on the microwave damping, attain a quantitative interpretation for the existence of the double resonance peaks and the positive shift. In particular, we will investigate the quantificational contributions of the mechanisms of Gilbert damping, two-magnon scattering and internal stray fields, and clearly illuminate the microwave damping mechanisms in the soft-magnetic films. This program could be a significant guide for the research on the microwave absorbing materials with intensive absorbing properties in wide frequency band.

在微波频率下具有宽损耗频带和高磁导率的纳米磁性薄膜在电磁屏蔽和雷达吸波领域具有极大的应用价值。与均匀磁性薄膜相比，高非均匀性磁性薄膜在保证高磁导率的同时，具有更宽的损耗频带，是当前最有潜力同时满足"宽、轻、强、薄"功能需求的吸波材料，但目前国内外对非均匀性散射损耗的来源和物理机制的认识并不全面。本项目创新性地引入非均匀散射损耗，采用多个磁性靶交替溅射和后续热退火等工艺调控薄膜结构的均匀性，制备具有多磁性相结构的FeCo基软磁薄膜，使其磁谱曲线具有多共振峰；深入研究纳米软磁薄膜中微波损耗特性与微观结构之间的关系，定量解释磁性薄膜磁谱曲线的多共振峰共存和"反常"频移现象；在理论上定量研究Gilbert损耗、双磁子散射、内部杂散场散射等机制对微波损耗性能和带宽特性的影响，阐明纳米磁性薄膜的微波损耗机制。本项目的实施可为宽频带、高损耗型磁性薄膜材料的研究提供理论指导。

非均匀性磁性薄膜在保证高磁导率的同时，可引入额外的损耗通道，因而具有更宽的损耗频带，是当前最有潜力同时满足"宽、轻、强、薄"功能需求的吸波材料。本项目采用多个磁性靶交替溅射和后续热退火等工艺调控薄膜结构的均匀性，引入非均匀结构引起的散射损耗，使制备的FeCo基软磁薄膜磁谱曲线具有多共振峰，从而拓宽薄膜损耗频带；在机理研究方面，深入探讨纳米软磁薄膜中微波损耗特性与微观结构之间的关系，定量解释磁性薄膜磁谱曲线的多共振峰共存和反常频移现象；在理论上推导Gilbert损耗、双磁子散射、内部杂散场散射等机制的理论公式，研究其对微波损耗性能和带宽特性的影响，阐明纳米磁性薄膜的微波损耗机制。本项目的实施可为宽频带、高损耗型磁性薄膜材料的研究提供有意义的指导。