A first-principles study of the magnetic properties in boron-doped ZnO

First-principles calculations based on density functional theory are performed to study the origin of ferromagnetism in boron-doped ZnO. It is found that boron atoms tend to reside at Zn sites. The induced Zn vacancy is a key factor for ferromagnetism in Zn1-xBxO (0相似文献   

Magnetic properties of a Pt/Co2FeAl/MgO structure with perpendicular magnetic anisotropy

Microstructures and magnetic properties of Ta/Pt/Co 2 FeAl（CFA）/MgO multilayers are studied to understand perpendicular magnetic anisotropy（PMA） of half-metallic full-Heusler alloy films.PMA is realized in a 2.5-nm CFA film with B2-ordered structure observed by a high resolution transmission electron microscope.It is demonstrated that a high quality interface between the ferromagnetic layer and oxide layer is not essential for PMA.The conversions between in-plane anisotropy and PMA are investigated to study the dependence of magnetic moment on temperature.At the intersection points,the decreasing slope of the saturation magnetization（M s） changes because of the conversions.The dependence of M s on the annealing temperature and MgO thickness is also studied.     

钙钛矿型HoNiO_3中电荷歧化的第一原理研究

应用第一原理的密度泛函方法 ,研究钙钛矿型过渡金属氧化物HoNiO3的电子结构 .HoNiO3在正交结构 (空间群为Pbnm)和单斜结构 (空间群为P2 1 n)的电子密度图表明Ni在正交相中只存在Ni3 一种组态 ,而在单斜相中则存在Ni( 3-δ) 和Ni( 3 δ) 两种不同的组态 .电荷歧化特征值δ可由Ni3d电子态密度中非键t2g部分反映 .通过t2g态密度在正交和单斜相的相对变化 ,可以算得δ值为 0 34± 0 0 1.     

铁磁/非磁金属异质结中的拓扑霍尔效应

在铁磁/非磁金属异质结中,界面处的Dzyaloshinskii-Moriya相互作用会诱导诸如磁性斯格明子等手性磁畴壁结构的形成.当巡游电子通过手性磁畴壁结构时,会获得一个贝里相位,而相应的贝里曲率则等效于一个外磁场,它将诱导额外的霍尔效应,即拓扑霍尔效应.拓扑霍尔效应是当前磁性斯格明子和自旋电子学研究领域的热点之一.本文由实空间贝里相位出发,简要介绍了拓扑霍尔效应的物理机制;然后着重讨论了铁磁/非磁金属异质结中的拓扑霍尔效应,包括磁性多层膜中和MnGa/重金属双层膜中的拓扑霍尔效应.这两种结构都可以通过改变材料的厚度、种类、生长方式等调控界面Dzyaloshinskii-Moriya相互作用,从而有效地调控磁性斯格明子和拓扑霍尔效应.     

LiAlyCo0.96-yMg0.04O2(y=0.3,0.7)的合成及相行为的DTA研究

用柠檬酸配位聚合法合成了LiAl_yCo_0.96-yMg_0.04O₂(y=0.3,0.7)粉体,采用DTA方法和X射线衍射分析研究了烧结温度对不同铝含量材料相行为的影响.实验结果表明,铝掺杂量低(y=0.3)时,在600℃烧结就可得到具有α-NaFeO₂结构的单相固溶体.而铝掺杂量高(y=0.7)时,在600和700℃烧结都有γ-LiAlO₂相出现,直到烧结温度升高到800℃才得到单相固溶体.