基于镧锰氧化物多维可调控的太赫兹复合超材料的电磁响应特性研究

Metamaterials have great application potential in functional devices and communication fields due to their unique properties. Currently, the internal mechanism of the properties in terahertz artificial materials is not completely clear yet and the methods of modulation lack of diversity. Lanthanum manganese oxides, which exhibit colossal magnetoresistance effect and plentiful phase diagrams, have giant application prospect in novel magnetic electronics devices. They are also the ideal multi-controlled materials by optical, thermal, electrical and magnetic methods. In this project, for the first time, we plan to introduce lanthanum manganese oxides into metamaterial system, design and fabricate terahertz composite metamaterials, then use optical pump-terahertz probe spectroscopy combining external thermal, electrical, or magnetic fields to study the multi-dimensional control in electromagnetic response. We focus on the influence of field-induced properties in lanthanum manganese oxides on electromagnetic coupling effect in terahertz composite metamaterials by obtaining amplitude, phase, and spectroscopy modulated information, and further find and analyze the possible new phenomena. This work could help us not only to know the material properties in the terahertz range and reveal their physical origin, but also to find out the promising physical effect for application and provide the experimental and theoretical foundation in exploiting terahertz wave manipulating devices.

超材料因其独特的物理特性在功能器件和通讯等领域具有不可估量的潜在应用价值。目前在太赫兹领域，这种人工结构材料特性的内部机制尚未完全清楚且调控方式较为单一。而具有庞磁电阻效应的镧锰氧化物具有丰富的物理特性，在新型磁电子学器件方面有巨大的应用前景，也是实现光、热、电和磁多手段调控的理想材料。本项目首次将镧锰氧化物材料引入超材料体系，设计和制备太赫兹复合超材料，在光泵浦-太赫兹探测超快光谱基础上施加温控、电控及磁控等外部激励，实现对复合超材料电磁响应的多维可调控。着重研究外场下镧锰氧材料场致变化特性对太赫兹复合超材料中的电磁场耦合效应的影响，获取振幅、相位、光谱等调制信息，发现有价值的新奇物理现象并加以理论分析。这不仅有助于我们了解该类材料在太赫兹频段的特性并揭示其物理来源，还有可能发现有重要应用价值的新物理效应，为开发太赫兹新型多功能调控器件、发展电磁波操控的新方法奠定实验和理论基础。

太赫兹超材料在功能器件和通讯等领域有潜在应用价值，但内部机制和调控方式还有待进一步研究。本项目设计模拟了超材料和复合材料在太赫兹频段的电磁响应，通过改变金属微结构的尺寸及形状来改变模式间的耦合。制备不同掺杂类型及厚度的薄膜材料，研究其在太赫兹频段的响应，筛选出较为适合做复合超材料基底的薄膜材料。进一步制备和优化太赫兹复合超材料，获得了材料介电性质对谐振强度、频率位置、偏振和带宽的影响的规律。利用结合了温控、光控等调控手段的太赫兹系统，研究外场下对太赫兹复合超材料的调控行为及其所揭示的内在物理过程。结合有效介质假设等，针对不同的耦合效应，建立了电路模型和耦合的洛伦兹模型。通过将外场调控的作用引入模型，进行相应条件下电磁场耦合系数等参数的理论计算，进一步揭示超材料特性的物理来源。研究工作为该类器件的模拟、实验和理论提供了思路和方法。