目的 从原子水平探究 Mn 掺杂 SiC 薄膜的磁性起源。 方法 采用射频磁控溅射技术制备不同掺杂浓度的 Mn 掺杂 SiC 薄膜,并采用 X 射线衍射技术、X 光电子能谱、同步辐射 X 射线近边吸收精细结构技术、物理性质测试系统对薄膜的结构、组分和磁性能进行研究。 结果 晶体结构和成分分析表明,1200 ℃退火后的薄膜形成了 3C-SiC 晶体结构,且随着 Mn 掺杂浓度的增加,3C-SiC 晶体的特征峰向低角度℃动。 在 Mn 掺杂浓度(以原子数分数计)为 3% ,5% ,7% 的薄膜中,掺杂的 Mn 原子以 Mn2+的形式存在;而在 9% Mn 掺杂的 SiC 薄膜中,则有第二相化合物 Mn4Si7 形成。 局域结构分析表明,薄膜中均不存在 Mn 金属团簇和氧化物,在 3% ,5% 和 7% Mn 掺杂的薄膜中,掺杂的 Mn 原子主要以代替 C 位的形式进入 3C-SiC 晶格中,而在 9% Mn 掺杂的薄膜中,掺杂的 Mn 原子以 C 替位形式和 Mn4Si7 共存。 磁性测试表明,制备的 Mn 掺杂 SiC 薄膜具有室温铁磁性,且饱和磁化强度随着 Mn 掺杂浓度的提高而增加。 结论 薄膜的室温铁磁性是本征的,磁性来源与掺杂的 Mn 原子以 Mn2+取代 SiC 晶格中 C 位后导致的缺陷有关,符合缺陷导致的束缚磁极子机制。

Objective To investigate the magnetic origin of Mn-doped SiC films from the atom level. Methods The films of Mndoped SiC were fabricated by radio frequency-magnetron sputtering. The structure, components and magnetic properties of films were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) and physical property measuring system (PPMS), respectively. Results The analysis of crystal structure and composition showed that the structure of 3C-SiC was formed in the films after 1200 ℃ anneal, and with the increasing of Mn content, the characteristic peaks of 3C-SiC moved to lower angle. In 3% , 5% and 7% Mn-doped SiC films, the doping Mn atoms existed in the form of Mn2+ ions, but in 9% Mn-doped SiC film, the second phase of compound Mn4 Si7 appeared. The study of local structure of films showed that there were no Mn clusters or Mn-related oxides. The doped Mn atoms existed in the form of substitution for C sites in 3C-SiC lattice in 3% , 5% and 7% Mn-doped SiC films, and in 9% Mn-doped SiC film there was a coexistence of C substitution and compound Mn4 Si7 . The magnetic measurement by PPMS showed that the Mn-doped SiC films were ferromagnetic at room temperature, and the saturation magnetization increased with the increasing of Mn content. Conclusion The magnetism of films is intrinsic and relevant to the defects caused by Mn in the form of Mn2+ substituted for C in 3C-SiC lattice and is accorded with the bound magnetic polarons (BMP) mechanism accused by defects.