Tuning of ferromagnetism through anion substitution in Ga-Mn-pnictide ferromagnetic semiconductors
Peter R. Stone, Jeffrey W. Beeman, Kin M. Yu, Oscar D. Dubon
备注：
14 pages, 4 figures. Accepted for publication in the Proceedings of the 24th International Conference on Defects in Semiconductors, which will be released in the journal Physica B: Condensed Matter
We have synthesized Ga1-xMnxAs1-yPy and Ga1-xMnxP1-yNy by the combination of ion implantation and pulsed-laser melting. We find that the incorporation of isovalent impurities with smaller atomic radii leads to a realignment of the magnetic easy axis in Ga1-xMnxP1-yNy/GaP and Ga1-xMnxAs1-yPy/GaAs thin films from in-plane to out-of-plane. This tensile-strain-induced magnetic anisotropy is reminiscent of that observed in Ga1-xMnxAs grown on larger lattice constant (In,Ga)As buffer layers indicating that the role of strain in determining magnetic anisotropy is fundamental to III-Mn-V materials. In addition, we observe a decrease in the ferromagnetic Curie temperature in Ga1-xMnxAs1-yPy with increasing y from 0 to 0.028. Such a decrease may result from localization of holes as the P/As ratio on the Group V sublattice increases.
Flatband-Induced Itinerant Ferromagnetism in RbCo$_2$Se$_2$
$A$ Co $_2$ Se $_2$（$A$ =K，Rb，Cs）是铁基超导体$A$ Fe $_2$ Se $_2$的同系物。从全面的研究RbCo $_2$硒$_2$通过测量的磁化强度，运输，中子衍射，角分辨光电子能谱，和第一性原理计算，我们确定了铁磁顺序伴随着轨道相关的自旋分裂的电子色散。此外，我们确定的有序矩占主导地位的$d_{x^2-y^2}$平带附近的费米能级，表现出最大的自旋分裂的铁磁过渡，这表明巡回起源的铁磁性。在铁基超导体的更广泛的背景下，我们发现这种$d_{x^2-y^2}$平带是铁硫属化物和铁磷属化物的能带结构的共同特征，可通过重电子掺杂。
Magnetic interactions in a proposed diluted magnetic semiconductor (Ba$_\text{1-x}$K$_\text{x}$)(Zn$_\text{1-y}$Mn$_\text{y}$)$_\text{2}$P$_\text{2}$
采用第一性原理电子结构计算方法，研究了BaZn $_2$ P $_2$基稀磁半导体（DMS）中的磁相互作用.对于一个典型的化合物Ba（Zn $_{0.944}$ Mn $_{0.056}$）$_2$ P $_2$，由于Mn原子间的超交换作用和不存在巡回载流子，短程反铁磁耦合占主导地位. K原子部分取代Ba原子，在P原子的$p$轨道上引入巡游空穴载流子，通过P原子和Mn原子之间的$p$-$d$杂化，将Mn原子的自旋极化空穴与远距磁矩连接起来，这对化合物的铁磁性是至关重要的。此外，施加静水压力首先增强然后降低（Ba $_{0.75}$ K $_{0.25}$）（Zn $_{0.944}$ Mn $_{0.056}$）$_2$ P $_2$中的铁磁耦合，转折点在15 GPa左右，这是由压力引起的电子离域变化和$p$ - $d$杂交的综合影响造成的。与BaZn $_2$ As $_2$基DMS相比，P取代As能有效地调制磁耦合.基于BaZn $_2$ P $_2$的DMS和基于BaZn $_2$ As $_2$的DMS的结果都表明，由阴离子桥接的最近的Mn-Mn对之间的鲁棒反铁磁（AFM）耦合对改善这种基于II-II-V的DMS材料的性能是有害的。
