“1111”型稀磁半导体的研究进展

The research progress of “1111” type diluted ferromagnetic semiconductor

我们成功地制备了载流子和自旋分离的"1111"型块材稀磁半导体(La,AE)(Zn,TM)AsO(AE=Ba,Sr;TM=Mn,Fe)居里温度TC可以达到40K.我们研究了载流子和局域磁矩对铁磁有序的调制作用,在(La1-xSrx)(Zn0.9Mn0.1)AsO(x=0.10,0.20,0.30)中,控制Mn的浓度为10%,改变Sr的掺杂浓度,当Sr的掺杂量为10%时,我们可以观测到～30 K的铁磁转变温度;而当Sr的掺杂量达到30%时,铁磁转变温度和有效磁矩都大幅度地降低.我们运用缪子自旋共振和中子散射等微观测量手段研究了该系列材料的自旋动力学,缪子自旋共振的测量表明铁磁有序转变发生在整个样品内,即样品是块材稀磁半导体;缪子自旋共振测量得到的"1111"型稀磁半导体静态局域场振幅as与居里温度TC的关系和(Ga,Mn)As,"111"型Li(Zn,Mn)As,以及"122"型(Ba,K)(Zn,Mn)2As2一致,表明这些体系拥有相同的磁性起源机制.我们对该系列稀磁半导体的研究有利于进一步揭示包括(Ga,Mn)As在内的稀磁半导体的磁性起源机制.

We successfully fabricated ＂1111＂ type bulk form diluted ferromagnetic semiconductors（DMS） with decoupled carriers and spins doping：（La,AE）（Zn,TM）AsO（AE Ba, Sr; TM = Mn, Fe）, of which the Curie temperature TCup to 40 K. We investigated the individual influence of carriers and local moments on the ferromagnetic ordering in（La1-xSrx）（Zn0.9Mn0.1）AsO by fixing Mn at the level of 0.10, and vary the doping levels of Sr. When the Sr doping level is 10%, a ferromagnetic ordering below ～ 30 K is observed. But both TCand saturation moments are heavily suppressed when the Sr doping level is increased to x= 0.30. We investigated the spin dynamics by microscopic techniques of μSR and Neutron Scattering. The results of μSR measurements indicate that the ferromagnetic order transition takes place in entire volume, namely, these DMSs are bulk nature. The μSR measurements also show an universal linear trend between the static internal field parameter as and the ferromagnetic Curie temperature TC for 1111-type system,（Ga,Mn）As, the 111- type system Li（Zn,Mn）As and the 122-type system（Ba,K）（Zn,Mn）2As2, which suggests that the exchange interaction supporting ferromagnetic coupling in these systems has a common origin. The researches on this series of DMS will be helpful to reveal the general mechanism of ferromagnetism shared in diluted ferromagnetic semiconductors including（Ga, Mn）As.