自旋和电荷分别掺杂的新一类稀磁半导体研究进展

Recent progress of a new type diluted magnetic semiconductors with independent charge and spin doping

稀磁半导体兼具半导体材料和磁性材料的双重特性,是破解摩尔定律难题的方案之一.我们团队通过提出自旋和电荷分别掺杂的机制,研制发现了一类新型稀磁半导体材料,为突破经典稀磁半导体材料自旋和电荷一体掺杂引起的材料制备瓶颈提供了有效解决方案.(Ba,K)(Zn,Mn)2As2(BZA)等新型稀磁半导体通过等价掺杂磁性离子引入自旋、异价非磁性离子掺杂引入电荷,实现了 230 K 的居里温度,刷新了可控型稀磁半导体的居里温度记录.本文重点介绍 1)几种代表性的自旋和电荷掺杂机制分离的新型稀磁半导体的发现与研制;2)新型稀磁半导体的子自旋弛豫与高压物性结构的调控;3)大尺寸单晶生长、基于单晶的安德烈夫异质结研制以及自旋极化率的测量.通过新材料设计研制、综合物性研究、简单原型器件构建的“全链条”模式研究,开拓了自旋电荷分别掺杂的稀磁半导体材料研究领域,展现了这类新型稀磁半导体材料潜在的光明前景.

Due to the potential applications for spintronics devices, diluted ferromagnetic semiconductors (DMS) havereceived extensive attention for decades. However, in classical Ⅲ-Ⅴ based DMS material, such as (Ga,Mn)As,heterovalent (Ga3+, Mn2+) doping results in lack of individual control of carrier and spin doping, and seriouslylimited chemical solubility. The two difficulties prevent furtherincrease of the Curie temperature of the ⅢⅤbased DMS. To overcome these difficulties, a series of new types of DMS with independent spin and chargedoping have been synthesized, such as Ⅰ-Ⅱ-Ⅴ based LiZnAs and Ⅱ-Ⅱ-Ⅴ based (Ba,K)(Zn,Mn)2As2. In thesenew materials, isovalent (Zn,Mn) substitution is only spin doping, while charge is independently doped byheterovalentsubstitution of non-magnetic elements. As a result (Ba,K)(Zn,Mn)2As2 obtains the reliable record ofCurie temperature (230 K) among DMS in which ferromagnetic ordering is mediated by itinerate carriers. Inthis review, we summarize the recent development of the new DMS materials with following aspects: 1) thediscovery and synthesis of several typical new DMS materials;2) physical properties studies with muon spinrelaxation and in-situ high pressure techniques;3) single crystal growth, Andreev reflection junction based onsingle crystal and measurements of spin polarization.