In掺杂对磁性半导体Li_(1.05)(Zn_(0.925),Mn_(0.075))As中铁磁序的调控

磁性半导体中磁矩受载流子调控形成有序态,但其机制尚存在着争议.本文利用高温固相反应法,通过(Zn^(2+),In^(3+))替换,即In^(3+)占据Zn^(2+)的晶格位置,在p型块状磁性半导体Li_(1.05)(Zn_(0.925),Mn_(0.075))As中引入n型载流子,成功合成了一系列Li_(1.05)(Zn_(0.925-y),Mn_(0.075),In_(y))As(y=0,0.05,0.075,0.1)新材料.在保持Mn掺杂浓度为7.5%不变时,仍可在所有In掺杂的样品中观察到铁磁转变.随着In掺杂浓度的增大,其居里温度被不断压制.样品的电阻率随着In掺杂浓度的增大而逐渐增大.实验结果表明,随着In的掺杂,Li_(1.05)(Zn_(0.925),Mn_(0.075)),As中原有的p型载流子被部分抵消,导致总载流子浓度降低,反映了n型载流子对Li_(1.05)(Zn_(0.925),Mn_(0.075))As中铁磁序的压制作用,同时也验证了载流子对磁性半导体中铁磁序的重要影响.

Observation of spin-glass behavior in 1111-type magnetic semiconductor(La,Ba)(Zn,Mn)SbO

We report the successful fabrication of a new 1111-type bulk magnetic semiconductor(La,Ba)(Zn,Mn)SbO through the solid solution of(La,Ba)and(Zn,Mn)in the parent compound LaZnSbO.The polycrystalline samples(La,Ba)(Zn,Mn)SbO crystallize into ZrCuSiAs-type tetragonal structure,which has the same structure as iron-based superconductor LaFeAsO_(1-δ).The DC magnetization measurements indicate the existence of spin-glass ordering,and the coercive field is up to~11500 Oe(1 Oe=79.5775 A·m^(-1)).The AC magnetic susceptibility further determines that the samples evolve into a conventional spin-glass ordering state below the spin freezing temperature T_(f).In addition,the negative magnetoresistance(MR≡[ρ(H)-ρ(0)]/ρ(0))reaches-88%under 9 T.

一种具有“1111”型结构的新型稀磁半导体(La_(1-x)Sr_(x))(Zn_(1-x)Mn_(x))SbO

利用高温固相反应法,成功合成了一种新型块状稀磁半导体(La_(1-x)Sr_(x))(Zn_(1-x)Mn_(x))SbO(x=0.025,0.05,0.075,0.1).通过(La^(3+),Sr^(2+))、(Zn^(2+),Mn^(2+))替换,在半导体材料LaZnSbO中分别引入了载流子与局域磁矩.在各掺杂浓度的样品中均可观察到铁磁有序相转变,当掺杂浓度x=0.1时,其居里温度Tc达到了27.1 K,2 K下测量获得的等温磁化曲线表明其矫顽力为5000 Oe.(La_(1-x)Sr_(x))(Zn_(1-x)Mn_(x))SbO与“1111”型铁基超导体母体LaFeAsO、“1111”型反铁磁体LaMnAsO具有相同的晶体结构,且晶格参数差异很小,为制备多功能异质结器件提供了可能的材料选择.