YIG/PST磁电复合薄膜的生长控制及其磁电调谐性能研究

Electrically and magnetically tunable composite thin films can overcome the limitations of ferrites and ferroelectrics, making it adapted for the tendency of integrated system, fast response and wide frequency band for microwave tunable devices, and thus have significant application prospect in communications, radar and radio-frequency systems. Microwave tunable materials with high tunability and low dissipation have been focus on current research. In this project, the lead strontium titanate (PST) with high tunability will be used as the ferroelectric layer for the first time, and the new YIG/PST magnetoelectric composite thin films will be fabricated by chemical solution methods,which are potential for realizing high tunability and low dissipation within relatively wide temperature range near room temperature. High quality YIG/PST thin films will be obtained by optimization of fabrication techniques. The introduction of ultra-thin TiOx buffer layer is masterly adopted to adjust the interface characteristics of YIG/PST, which will realize the oriented growth of the thin films. The relationship between the microstructure and magnetoelectric properties of the YIG/PST thin films will be investigated. The evolution of the ferromagnetic, ferroelectric, magntoelectric effect, and electrically and magnetically tunability of the composite thin films under applied magnetic field, electric field and temperature will also be studied, together with the relationship between the magntoelectric coupling effects and electric and magnetic tunability. The mechanism of electrically and magnetically tunability in ferrite/ferroelectric composite thin films will be revealed, which will increase the design freedom of microwave devices and lay the foundations for promoting the development of multifunctionality and practicalization of the microwave tunable devices.

磁电复合薄膜能克服铁氧体或铁电体的局限性，适应微波调谐器件集成化、快响应、宽频带的发展趋势，在通信、雷达、射频系统等领域具有重要的应用前景。探索调谐率高和损耗低的微波调谐材料是当前的研究热点。本项目首次采用具有优异介电可调性的钛酸锶铅(PST)作铁电层，利用化学溶液法构筑一种新型的YIG(钇铁石榴石)/PST磁电复合薄膜，可望在室温较宽的温度范围内实现高调谐率和低损耗。通过优化生长工艺，制备优质YIG/PST薄膜；巧妙引入超薄TiOx缓冲层，调控薄膜的界面特性，实现磁电复合薄膜择优取向生长。研究YIG/PST复合薄膜的微结构和磁电特性之间的关联性，复合薄膜的铁磁性能、铁电性能、磁电耦合效应、磁电调谐性能随磁场、电场、温度的演变规律，以及磁电耦合效应与磁电调谐性能之间的关系，揭示铁氧体/铁电体复合薄膜磁电调谐的物理机制，为提高微波器件设计的自由度，促进器件的多功能化和实用化发展奠定基础。

磁电复合薄膜能克服铁氧体或铁电体的局限性，适应微波调谐器件集成化、快响应、宽频带的发展趋势，在通信、雷达、射频系统等领域具有重要的应用前景。探索调谐率高和损耗低的微波调谐材料是当前的研究热点。本项目采用磁控溅射法，在GGG衬底上实现了（111）取向YIG薄膜的生长。首次利用化学溶液法，在Si 衬底上实现了YIG 薄膜的生长，在较低的退火温度（750oC）时，YIG 薄膜的磁性能优于文献报道的 Si 衬底上制备的 YIG 多晶薄膜。采用化学溶液法和磁控溅射法，巧妙引入TiOx 、Pt、LNO缓冲层，调控薄膜的界面特性，实现新型磁电复合薄膜YIG/LNO/PST、YIG/LNO/PZT择优取向生长和构筑新型薄膜-陶瓷复合结构YIG/PMN-PZT。通过优化生长工艺，制备了优质 YIG/PST（100） 薄膜。当施加磁场强度为 600 Oe 时，复合薄膜的磁导率变化率可达 91.2%，同时具有更高的介电调谐率 η=74.8%@400 kV/cm。在室温较宽的温度范围内实现高调谐率和低损耗。说明 PST/LNO/YIG和YIG/PMN-PZT复合薄膜在磁场和电场的作用下，同时具备高的磁场可调性和电场可调性。成功构筑了YIG/LNO/PZT磁电复合薄膜，复合薄膜不但没有降低各相原有的优异的磁性能和电性能，而且还略微增加了相应的磁、电性能，为微波磁电耦合效应的研究奠定了材料基础。系统研究了复合薄膜的微结构和磁电特性之间的关联性，复合薄膜的铁磁性能、 铁电性能、磁电耦合效应、磁电调谐性能随磁场、电场、温度的演变规律，以及磁电耦合效应与磁电调谐性能之间的关系，揭示铁氧体/铁电体复合薄膜磁电调谐的物理机制，为提高微波器件设计的自由度，促进器件的多功能化和实用化发展奠定基础。