【摘要】 通过X射线吸收近边结构(XANES)、超导量子干涉仪和第一性原理计算研究了脉冲激光沉积法(PLD)制备的Ni1-xMnxO(0.01≤x≤0.05)薄膜的微观结构和磁学性质.X射线吸收近边结构表明,当x≤0.03时,掺杂的Mn替代了NiO晶格中的Ni原子,并且以混合价态(+2/+3)的形式存在.当x>0.03时,掺杂的部分Mn离子形成了类Mn2O3杂相.磁性测量表明,随着Mn含量从0.01增加到0.03,Ni1-xMnxO薄膜的饱和磁矩从0.3μB/Mn增加到了0.45μB/Mn.基于第一性原理计算,我们提出Mn3+离子之间通过Ni空位表现出了铁磁性耦合,Mn2+离子之间则通过超交换作用表现出了反铁磁耦合.更多还原

【Abstract】 The microstructural and magnetic properties of Ni1-xMnxO(0.01≤x≤0.05)thin films prepared by pulsed laser deposition(PLD)were studied by combining X-ray absorption near edge structure(XANES)spectroscopy,superconducting quantum interference device(SQUID)and first-principles calculations.XANES results at Mn K-edge show that at the low Mn doping level of x≤0.03,the Mn ions in the mixed oxidation valence state(+2/+3)are incorporated substitutionally into the NiO host,while at higher doping level of x>0.03 Mn2O3-like impurity phase is formed.Magnetization measurements indicate that the saturation magnetic moment of Ni1-xMnxO film increases from 0.3to 0.45μB/Mn as the Mn content rises from 0.01 to 0.03.It is proposed that interactions between Mn3+ions mediated by Ni vacancies exhibit ferromagnetic coupling,while interactions between Mn2+ions exhibit antiferromagnetic coupling through superexchange interaction.更多还原