Theory of tunable magnetoelectric inductors in ferrite-piezoelectric layered composite

• Published in: Journal of physics. D, Applied physics Applied physics, 2019-04, Vol.52 (16), p.165001
• Main Authors: Zhang, Jitao, Chen, Dongyu, Filippov, D A, Geng, Shengtao, Li, Kang, Zhang, Qingfang, Jiang, Liying, Wang, Xiaolei, Zhu, Weiwei, Cao, Lingzhi, Srinivasan, Gopalan
• Format: Article
• Language: English
• Subjects: converse magnetoelectric effects; ferrite; tunable inductors
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/1361-6463/ab01a3

A theoretical model was developed for permeability-induced inductance variations under influences of H/E field applications in bulk composite of polycrystalline spinel ferrites and piezoelectric ceramics with coil wound around. Strain-mediated magnetization changes in ferrites facilitate the permeability variations and a significant tunability in inductance from converse magnetoelectric coupling mechanisms can be achieved as expected. Modeling the inductance variations, i.e. inductance responses with frequency, was performed in terms of thickness, frequency, Young's modulus, density as well as resonance dymanic at mechanical electromagnetic resonance frequency. From the magnetostrictive/piezoelectric constitutive equations in consideration of boundary conditions, we derive permeability expressions to allow for a quantitative description of inductance traces involved magnetic relaxation occurring around longitudinal acoustic mode in the presence of H/E field applications. The model was applied to a specific ferrite-piezoelectric tunable inductor of Ni0.7Zn0.3Ga0.02Fe1.98O4/PZT/Ni0.7Zn0.3Ga0.02Fe1.98O4 trilayer with coil. Then, we explicitly calculate the amplitude and tendency of inductance variations with frequency using the theory and evaluate the accordance with the corresponding experimental findings. The theory is of importance for studies on the underlying physics such field-induced permeability variations and resonance dynamics in ME tunable inductor devices. In particular, it helps to explain the recent measurements for which magnetic relaxation phenomenon occurring in typical inductance versus frequency characteristics.