Density functional theory with local spin density approximation has been used to propose possible room temperature ferromagnetism in N-doped NaCl-type BaO. Pristine BaO is a wide bandgap semiconductor, however, N induces a large density of states at the Fermi level in the nonmagnetic state, which suggests magnetic instability within the Stoner mean field model. The spin-polarized calculations show that N-doped BaO is a true half- metal, where N has a large magnetic moment, which is mainly localized around the N atoms and a small polarization at the O sites is also observed. The origin of magnetism is linked to the electronic structure. The ferromagnetic(FM) and antiferromagnetic (AFM) coupling between the N atoms in BaO reveal that doping N atoms have a FM ground state, and the calculated transition temperature ($T_{C}$), within the Heisenberg mean field theory, theorizes possible room temperature FM in N-doped BaO. Nitrogen also induces ferromagnetism when doping occurs at surface O site and has a smaller defect formation energy than the bulk N-doped BaO. The magnetism of N-doped BaO is also compared with Co-doped BaO, and we believe that N has a greater potential for tuning magnetism in BaO than Co.
Nitrogen-Vacancy-Mediated Magnetism in Sputtered GdN Thin Films
Indian Institute of Science（印度科学研究所）；Jawaharlal Nehru Center for Advanced Scientific Research（贾瓦哈拉尔·尼赫鲁高级科学研究中心）；Indian Institute of Technology Madras（马德拉斯印度理工学院）；IISER Thiruvananthapuram（特凡纳普拉姆印度科学教育研究院）；BITS Pilani K. K. Birla Goa Campus（比拉工业与科学研究所皮拉尼校区K.K.比尔拉果阿分校）
Nonmagnetic-Doping Induced Quantum Anomalous Hall Effect in Topological Insulators
在磁掺杂拓扑绝缘体中实验观察到量子反常霍尔效应。然而，超低温（通常低于300 mK），这主要是由于不均匀的磁性掺杂，成为一个艰巨的挑战，潜在的应用。本文提出了一种\textit{nonmagnetic}掺杂策略，在拓扑绝缘体中产生铁磁性并实现QAHE。我们数值计算表明，磁矩可以诱导由氮或碳取代在Bi $_2$ Se $_3$，Bi $_2$ Te $_3$，和Sb $_2$ Te $_3$，但只有氮掺杂的Sb $_2$ Te $_3$表现出长程铁磁性和保持大的体带隙。我们进一步表明，其相应的薄膜可以在17-29开尔文的温度下窝藏QAHE，这比类似系统中的典型温度高两个数量级。我们提出的\textit{nonmagnetic}掺杂方案可能为拓扑绝缘体中高温QAHE的实验实现提供新的思路。
Pressure Dependence of Ferromagnetism in Uranium Hydride UH$_3$ up to 20 GPa Revealed by NV Centers Magnetometry
CEA DAM, DIF；Université Paris-Saclay（巴黎萨克雷大学）；CEA（法国原子能和替代能源委员会）；Laboratoire Matière en Conditions Extrêmes（极端条件物质实验室）；CNRS（法国国家科学研究中心）；ENS Paris-Saclay（巴黎萨克雷高等师范学院）；Centralesupelec（中央理工-电院）
Exchange Interaction and $T_c$ in Alkaline-earth-metal-oxide-based DMS without Magnetic Impurities: First Principle Pseudo-SIC and Monte Carlo Calculation
通过第一性原理计算，探讨了碱土金属氧化物中引入碳原子诱导半金属铁磁性的前景。利用类赝势自相互作用修正的局域自旋密度方法计算了体系的电子结构和交换耦合常数，讨论了体系铁磁性的起源。居里温度（$T_c$）也通过采用蒙特卡罗模拟预测。结果表明，考虑电子自相互作用后，C在主体材料中诱导的半金属铁磁性比标准LDA情形更稳定，C的$2p$电子态在带隙中的局域化程度更高，短程交换作用占优势.虽然MgO $_{1-x}$ C $_x$中的铁磁性由于$1st$ -最近邻对的交换相互作用而稳定，并且可能在较高的$x$下被反铁磁性超交换相互作用抑制，但是CaO $_{1-x}$ C $_x$、SrO $_{1-x}$ C $_x$和BaO $_{1-x}$ C $_x$中的铁磁性通过$1st$ -和$2nd$ -最近邻对两者而稳定，而$T_c$随C浓度单调增加。
