Electromagnetic eigenwaves in a weak ferromagnetic with anisotropy of the “easy plane” under magnetization in this plane are investigated. It is shown that at frequencies of anti-resonances the weak ferromagnetic can be considered as environment with characteristic impedance close to zero. The polarization of eigenwaves in such environment is analyzed on the example of high-temperature weak ferromagnetics—hematite and iron borate. It is proposed to consider the weak ferromagnet-metal structure as an element of the metasurface with a controlled phase shift of the reflected wave. A tunable Fabry-Perot resonator with a weak ferromagnet-metal structure (ferromagnet is of sub-wave thickness) is considered and the corresponding frequency-field dependencies in the sub-terahertz range are studied. It is shown that such resonator combines rather high Q-factor with a possibility of magnetic tuning of its resonance frequency. The maximum local slope of the field dependence of the resonator frequency reaches 0.3 MHz/Oe using a hematite layer and 0.6 MHz/Oe using an iron borate layer of 10 µm thickness. The resonator unloaded quality factor for the main mode varies within 300–1400 and 250–1000, respectively.

中文翻译：

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基于弱铁磁的可调谐反射结构及其在可调谐亚太赫兹谐振器中的应用

研究了在该平面磁化作用下“易平面”具有各向异性的弱铁磁体中的电磁本征波。结果表明，在反谐振频率下，弱铁磁体可以被认为是特征阻抗接近于零的环境。以高温弱铁磁体——赤铁矿和硼酸铁为例，分析了这种环境中本征波的极化。建议将弱铁磁体金属结构视为具有反射波受控相移的超表面元素。考虑了具有弱铁磁体-金属结构（铁磁体具有亚波厚度）的可调法布里-珀罗谐振器，并研究了亚太赫兹范围内的相应频率-场相关性。结果表明，这种谐振器将相当高的 Q 因子与其谐振频率的磁调谐的可能性相结合。使用赤铁矿层时，谐振器频率场相关性的最大局部斜率达到 0.3 MHz/Oe，使用 10 µm 厚的硼酸铁层时达到 0.6 MHz/Oe。主模式的谐振器卸载品质因数分别在 300-1400 和 250-1000 内变化。