【摘要】 太赫兹(terahertz, THz)辐射的光子能量极低，不会对分子、晶格造成有害的电离，且生物大分子的振动和转动频率均在THz波段，因而THz在生物医学上的应用引起了广泛的关注。然而，目前的商用THz源无法兼顾室温工作、低成本、小型化等生物医学应用方面的需求。自旋THz源辐射效率高，可实现THz偏振调谐，有望打破生物医学领域的应用瓶颈。为系统全面地对自旋THz源的发射机理和调控方式进行研究，并对THz源在生物医学方面的应用展开分析，从光电流的来源入手梳理了THz产生机制并总结了其发射机理。根据生物医学的应用需求，分别从材料、生长条件等角度分析了多种自旋材料中的THz发射优化方式，揭示了THz发射与材料性质、外界环境等因素的依赖关系，探究了自旋THz源的优势和调控手段。结合生物医学检测的需求与特点，以铁磁/非铁磁金属异质结和铁磁/拓扑绝缘体异质结两种发射源为例介绍了自旋THz源在生物医学领域的初步探索，并对其未来的应用前景和发展方向做出展望。更多还原

【Abstract】 Recently, terahertz(THz) spectrum has been proved to be one of the most potential candidates in the biomedical field on account of low photon energy, harmlessness and containing the vibration and rotation frequencies of bio-macromolecules. For the convenience of detection, an inexpensive, portable and reliable equipment is required at room temperature. However, the commercial THz sources available are not adequate. An emerging replacement, the spintronic THz emitter, is moving towards the biomedical application. These spintronic THz sources with a thickness of several nanometers, such as topological insulator(TI) and ferromagnetic/nonmagnetic(FM/NM) heterostructure, can generate high-power terahertz wave under the excitation of femtosecond laser. In addition, THz polarization tuning can be realized by changing the direction of the magnetic field or the polarization state of the pump, which can meet the needs of THz circular dichroism(TCD) spectrum detection in the biomedical field. Above all, a multi-functional, on-chip tunable, real-time biomedical spintronic terahertz source device is expected to be realized by combining spintronics, the important technological means in the post-Moore era. In this paper, beginning with the photocurrent generation mechanism of TI and FM/NM, we gained the THz emission mechanism and impact factor. Then, THz emission optimization methods of various spintronic materials were analyzed from the perspectives of materials and growth methods on the basis of the requirements of biomedical applications. Moreover, the dependence of THz emission on material properties and external environment was revealed, and the advantages and control methods of spintronic THz source were explored. We also concluded that FM/TI was suitable for biomedical detection theoretically because its THz amplitude is comparable to that of ZnTe, and the polarization can be adjusted arbitrarily. Finally, combined with the requirements and characteristics of biomedical detection, taking FM/NM and FM/TI as examples, the scene and methods of spintronic THz source in the field of biomedical detection were introduced, and its future development direction was prospected.更多还原