Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Nat Commun. 2011 Aug 9;2:422. doi: 10.1038/ncomms1425.
In a prototypical ferromagnet (Ga,Mn)As based on a III-V semiconductor, substitution of divalent Mn atoms into trivalent Ga sites leads to severely limited chemical solubility and metastable specimens available only as thin films. The doping of hole carriers via (Ga,Mn) substitution also prohibits electron doping. To overcome these difficulties, Masek et al. theoretically proposed systems based on a I-II-V semiconductor LiZnAs, where isovalent (Zn,Mn) substitution is decoupled from carrier doping with excess/deficient Li concentrations. Here we show successful synthesis of Li(1+y)(Zn(1-x)Mn(x))As in bulk materials. Ferromagnetism with a critical temperature of up to 50 K is observed in nominally Li-excess (y=0.05-0.2) compounds with Mn concentrations of x=0.02-0.15, which have p-type metallic carriers. This is presumably due to excess Li in substitutional Zn sites. Semiconducting LiZnAs, ferromagnetic Li(Zn,Mn)As, antiferromagnetic LiMnAs, and superconducting LiFeAs systems share square lattice As layers, which may enable development of novel junction devices in the future.
在基于 III-V 半导体的典型铁磁体 (Ga,Mn)As 中，二价 Mn 原子取代三价 Ga 位会导致化学溶解度严重受限，并且仅能获得亚稳的薄膜形式的样品。通过 (Ga,Mn) 取代掺杂空穴载流子也会阻止电子掺杂。为了克服这些困难，Masek 等人从理论上提出了基于 I-II-V 半导体 LiZnAs 的体系，其中等价（Zn,Mn）取代与过量/缺乏 Li 浓度的载流子掺杂解耦。在这里，我们展示了在块状材料中成功合成 Li(1+y)(Zn(1-x)Mn(x))As。在名义上 Li 过量（y=0.05-0.2）的化合物中观察到高达 50 K 的居里温度的铁磁性，其中 Mn 浓度为 x=0.02-0.15，具有 p 型金属载流子。这可能是由于替代 Zn 位中的过量 Li 所致。共享四方晶格 As 层的 LiZnAs、铁磁 Li(Zn,Mn)As、反铁磁 LiMnAs 和超导 LiFeAs 体系可能会在未来开发出新型结器件。
