Regulation of dielectric properties for YIG/LFO composite thin films through varying the layer thickness ratio

Yttrium iron garnet (Y₃Fe₅O₁₂, YIG) ferrites are usually composited with dielectric materials to fulfill performance requirements. In this work, Y₃Fe₅O₁₂/LiFe₅O₈ (YIG/LFO) composite dielectric films were fabricated via chemical solution deposition, and the layer thickness ratio was varied to achieve differing properties. Dielectric spectrum analysis shows that a YIG/LFO thickness ratio of 3:7 provides a dielectric constant of 19.24 at 100 Hz, primarily due to the enhanced internal electric field. When the thickness ratio is 5:5, the dielectric tunability at 20 kHz reaches −55.9 %, which is 5.75 times greater than the value observed at a 7:3 ratio due to the increased oxygen vacancy concentration. However, the 7:3 composite film exhibited outstanding temperature stability within the temperature range of −120 °C–120 °C. Theoretical calculations show that oxygen vacancies significantly enhance dielectric tuning by altering the electronic structure and physical properties of these composite materials.