面向应用的新一代稀磁半导体研究进展

Recent advances in application-oriented new generation diluted magnetic semiconductors

稀磁半导体具有能同时调控电荷与自旋的特性,是破解摩尔定律难题的候选材料之一.我们团队率先提出了稀磁半导体中自旋和电荷掺杂分离的机制,探索并研制了新一代稀磁半导体材料,为突破经典稀磁半导体材料的制备瓶颈提供了有效解决方案.以(Ba,K)(Zn,Mn)_(2)As_(2)等为代表的新一代稀磁半导体,通过等价态的Mn掺杂引入自旋、异价态的非磁性离子掺杂引入电荷,成功实现了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.本文将重点介绍几种代表性的新一代稀磁半导体的设计与研制、新一代稀磁半导体的综合物性表征、大尺寸单晶生长以及基于单晶的安德烈夫异质结研制.我们团队通过新一代稀磁半导体的新材料设计研制、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,充分展现了自旋和电荷掺杂分离的新一代稀磁半导体材料潜在应用前景.

Diluted ferromagnetic semiconductors(DMSs) have attracted widespread attention in last decades,owing to their potential applications in spintronic devices.But classical group-Ⅲ-Ⅳ,and-Ⅴ elements based DMS materials,such as(Ga,Mn)As which depend on heterovalent(Ga~(3+),Mn~(2+)) doping,cannot separately control carrier and spin doping,and have seriously limited chemical solubilities,which are disadvantages for further improving the Curie temperatures.To overcome these difficulties,a new-generation DMS with independent spin and charge doping have been designed and synthesized.Their representatives are Ⅰ-Ⅱ-Ⅴ based Li(Zn,Mn)As and Ⅱ-Ⅱ-Ⅴ based(Ba,K)(Zn,Mn)_2As_2.In these new materials,doping isovalent Zn~(2+) and Mn~(2+) introduces only spins,while doping heterovalent non-magnetic elements introduces only charge.As a result,(Ba,K)(Zn,Mn)_2As_(2) achieves Curie temperature of 230 K,a new record among DMS where ferromagnetic orderings are mediated by itinerate carriers.Herein,we summarize the recent advances in the new-generation DMS materials.The discovery and synthesis of several typical new-generation DMS materials are introduced.Physical properties are studied by using muon spin relaxation,angle-resolved photoemission spectroscopy and pair distribution function.The physical and chemical pressure effects on the title materials are demonstrated.The Andreev reflection junction based on single crystal and the measurement of spin polarization are exhibited.In the end,we demonstrate the potential multiple-parameter heterojunctions with DMSs superconductors and antiferromagnetic materials.