Kumar Raj, Liu Yang, Li Jia, Iyer Shanthi, Reynolds Lewis
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA.
Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, Greensboro, NC, 27401, USA.
Sci Rep. 2020 Jun 2;10(1):8995. doi: 10.1038/s41598-020-65805-4.
Intrinsic and Te-doped GaAsSb nanowires with diameters ~100-120 nm were grown on a p-type Si(111) substrate by molecular beam epitaxy (MBE). Detailed magnetic, current/voltage and low-energy electron energy loss spectroscopy measurements were performed to investigate the effect of Te-doping. While intrinsic nanowires are diamagnetic over the temperature range 5-300 K, the Te-doped nanowires exhibit ferromagnetic behavior with the easy axis of magnetism perpendicular to the longitudinal axis of the nanowire. The temperature dependence of coercivity was analyzed and shown to be in agreement with a thermal activation model from 50-350 K but reveal more complex behavior in the low temperature regime. The EELS data show that Te doping introduced a high density of states (DOS) in the nanowire above the Fermi level in close proximity to the conduction band. The plausible origin of ferromagnetism in these Te-doped GaAsSb nanowires is discussed on the basis of d ferromagnetism, spin ordering of the Te dopants and the surface-state-induced magnetic ordering.
通过分子束外延（MBE）在p型Si(111)衬底上生长了直径约为100 - 120nm的本征和碲掺杂的GaAsSb纳米线。进行了详细的磁性、电流/电压和低能电子能量损失谱测量，以研究碲掺杂的影响。虽然本征纳米线在5 - 300K的温度范围内是抗磁性的，但碲掺杂的纳米线表现出铁磁行为，其易磁化轴垂直于纳米线的纵轴。分析了矫顽力的温度依赖性，结果表明在50 - 350K范围内与热激活模型一致，但在低温区域表现出更复杂的行为。电子能量损失谱数据表明，碲掺杂在纳米线中费米能级以上、紧邻导带处引入了高密度的态（DOS）。基于d铁磁性、碲掺杂剂的自旋有序和表面态诱导的磁有序，讨论了这些碲掺杂的GaAsSb纳米线中铁磁性的可能起源。
