反赫斯勒化合物基亚铁磁性半导体的设计、合成及性能

The next-generation memory and logic devices, such as spin-transfer torque magnetoresistive random access memory (STT-MRAM), make progress towards significant downscaling of the devices dimensions, ultrafast read and write speed, and greatly reduced power consumption, which expects excellent spintronics materials possessing both high spin polarization and high spin injection efficiency simultaneously. So far, no material can be a perfect candidate. Taking advantage of the characteristic of heusler compounds that the displacement(or replacement) of elements and the change of degree of chemical order lead to their diversified band structure and properties, this project is going to prepare inverse heusler structured ferrimagnetic semiconductor thin film materials with band structure lying between half metallic ferromagnet and semiconductor using ion beam sputtering film deposition technique. In addition, synthetic ferrimagnetic semiconducting composite materials composed of inverse heusler structured half metallic ferrimagnet/diluted magnetic semiconductor multilayered stacks are also fabricated based on the structure compatibility between heusler compounds and zinc-blende semiconductor. Meanwhile, methods and mechanism are also studied for understanding the modulation of band structure of these materials and the interaction between the heusler-structured half metallic ferrimagnet and the diluted magnetic semiconductor. Via this project we expect to obtain new-style inverse heusler compound based ferrimagnetic semiconductor materials with high curie temperature and spin polarization, high spin injection efficiency and low net magnetic moment and establish optimized preparation technics and the mechanism of band structure modulation. This work provides new scientific and technical guidance for the design and control of spintronics devices in the future.

实现自旋转移力矩磁阻随机存储器等下一代信息存储和逻辑器件的关键是获得兼具高自旋极化和高自旋注入效率的自旋电子材料。本项目针对赫斯勒化合物通过元素占位、替代和原子有序度变化可实现不同能带结构的特点，采用离子束溅射等薄膜沉积手段制备兼具半金属铁磁体和半导体能带结构的新型反赫斯勒结构亚铁磁性半导体薄膜；根据赫斯勒化合物和闪锌矿型半导体的结构相容性，用反赫斯勒结构半金属亚铁磁体和稀磁半导体合成人工亚铁磁性半导体复合材料；探讨该类新型化合物能带结构调制以及半金属亚铁磁体和稀磁半导体相互作用的方法和机理。项目预期将获得具有高居里温度和自旋极化、高自旋注入效率、低净磁矩的反赫斯勒化合物基亚铁磁性半导体材料的薄膜沉积工艺并确立能带调制机理。研究成果可为下一代自旋电子器件的设计和操控提供新的思路和科学依据。

实现自旋转移力矩磁阻随机存储器等下一代信息存储和逻辑器件的关键是获得兼具高自旋极化和高自旋注入效率的自旋电子材料。本项目采用磁控溅射、分子束外延等薄膜沉积手段制备兼具半金属铁磁体和半导体能带结构的新型赫斯勒结构亚铁磁性半导体薄膜。成功制备得到Ti2MnAl自旋零禁带半导体薄膜材料，该材料性能优越，是一种极具应用潜力的自旋电子材料。本项目还创新性地根据赫斯勒化合物和闪锌矿型半导体的结构相容性，在实验上成功用赫斯勒结构半金属铁磁体和稀磁半导体合成新型超晶格自旋电子材料，并探讨该类新材料能带结构调制的方法和机理。新型超晶格自旋电子材料也具有预期的良好性能。项目基本实现了预期的研究目标，研究成果可为下一代自旋电子器件的设计和操控提供新的思路和科学依据。

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