空间限域磁有序结构增强的高性能热电材料构筑及新输运机制研究

目前，基于晶格和电荷自由度的传统热电材料性能优化方法，往往受限于热电参数之间的相互制约关系，使得热电优值的进一步提高面临巨大困境，亟需在新尺度、新自由度下发展突破性的输运性能调控手段。本项目拟通过在热电材料体系中引入空间限域磁有序结构，并将其作为基本的功能单元，在保证体系载流子迁移率的同时，增加新的自旋及轨道自由度。研究磁性功能单元磁有序态、磁耦合强度、磁相变、内磁场以及形态、尺寸、分布等本征特性对热电材料载流子输运、声子传导及电-声子相互作用的影响规律及调控机制，设计和构筑出提升室温区热电材料转换性能的关键磁性功能单元。发展“自下而上”的制备方法，调控功能单元的空间分布，研究空间有序引发的磁性功能单元之间磁耦合、磁振子传输及其对热电性能的增强效应，发掘提升近室温区热电材料性能的新输运机制。充分释放体系的自旋和轨道自由度，实现热电参数的解耦合调控，取得热电转换效率的突破性进展。

At present, the traditional optimization approaches for thermoelectric materials based on lattice and charge degrees of freedom are often limited by the adverse dependence of thermoelectric parameters, which makes the further improvement of thermoelectric figure of merit facing great difficulties. Therefore, it is urgent to develop revolutionary regulation methods for transport properties under new scales and new degrees of freedom. This project is devoted to introduce spatially confined magnetic ordered structures into the thermoelectric material systems as functional units, which can introduce new spin and orbital degrees of freedom into the system without deteriorating the carrier mobility. The influence and regulation mechanism for intrinsic properties of the functional units, such as magnetic ordering states, magnetic coupling strength, magnetic phase transitions, internal magnetic fields, morphologies, sizes and distributions, on the carrier transport, phonon conduction and electron-phonon interaction in thermoelectric materials will be investigated. Key magnetic functional units that can improve the conversion efficiencies of room-temperature thermoelectric materials will be designed and constructed. Furthermore, this project will develop "bottom-up" preparation methods to regulate the spatial arrangement of the functional units, and study the magnetic coupling and propagation process of magnons between the magnetic functional units, as well as their enhancing effects on thermoelectric properties. New transport mechanisms to improve the performance of thermoelectric materials near room temperature will be discovered. Through full release of the spin and orbital degrees of freedom, the decoupled regulation of thermoelectric parameters will be realized, and breakthrough progress in thermoelectric conversion efficiency will be achieved.