“1111” 型稀磁半导体的研究进展
摘要
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 TC up to 40 K. We investigated the individual influence of carriers and local moments on the ferromagnetic ordering in (La<sub>1-<italic>x</italic></sub>Sr<sub><italic>x</italic></sub>)(Zn<sub>0.9</sub>Mn<sub>0.1</sub>)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 TC and saturation moments are heavily suppressed when the Sr doping level is increased to <italic>x</italic>= 0.30. We investigated the spin dynamics by microscopic techniques of mSR and Neutron Scattering. The results of mSR 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 a<sub>s</sub> and the ferromagnetic Curie temperature T<sub>C</sub> for 1111-type system, (Ga,Mn)As, the 111- type system Li(Zn,Mn)As and the 122-type system (Ba,K)(Zn,Mn)<sub>2</sub>As<sub>2</sub>, 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.