Acoustic resonators based on antiferromagnetic crystals of “easy plane” type, like $\alpha $ -Fe ₂ O ₃ or FeBO ₃ , are of interest for applications in magnetoacoustic sensors of electrical and mechanical values because of high sensitivity of their resonance frequency to variations of external magnetic field or mechanical stress. One of the requirements for magnetic control of resonators is a single-value dependence of resonance frequency on magnetic field strength. This requirement is violated when the geometry of resonator allows for crossover of acoustic modes in the range of magnetic field variation. Designing of resonators with frequency control in a wide range requires knowledge of field-dependent acoustic parameters of the crystals and appropriate method for calculation of the resonator eigenfrequencies. In this letter, we present the complete set of acoustic parameters deduced for $\alpha $ -Fe ₂ O ₃ single crystal that are used for simulation of acoustic mode structures and spectra of vibrations in disk resonator. The results of simulation using COMSOL Multiphysics software are compared with experimental measurements carried out on two resonators of different ratios of sizes that illustrating continuous and discontinuous dependence of the resonance frequency on the magnetic field. Prevention of discontinuity by correction of the resonator geometry is demonstrated.

中文翻译：

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磁声谐振器的宽范围频率控制

基于“易平面”型反铁磁晶体的声谐振器，例如 $ \ alpha $ -Fe ₂ O ₃或FeBO ₃ 由于其共振频率对外部磁场或机械应力的变化具有很高的敏感性，因此在电子和机械值的磁声传感器中的应用引起了人们的关注。对谐振器进行磁控制的要求之一是谐振频率对磁场强度的单值依赖性。当谐振器的几何形状允许声学模式在磁场变化范围内交叉时，将违反此要求。设计具有宽范围频率控制的谐振器需要了解晶体的场相关声学参数，以及用于计算谐振器本征频率的适当方法。在这封信中，我们介绍了推导的完整声学参数集 $ \ alpha $ -Fe ₂ O ₃单晶，用于模拟磁盘谐振器中的声模结构和振动谱。使用COMSOL Multiphysics软件进行的仿真结果与在两个不同尺寸比率的谐振器上进行的实验测量结果进行了比较，这些测量结果说明了谐振频率对磁场的连续和不连续依赖性。证明了通过校正谐振器几何形状来防止不连续性。