【摘要】 在氧离子注入的AlN薄膜AlN:O_{（5×10）¹6}(剂量为5×10¹⁶ cm^-2)和AlN:O_{（2×10）¹7},(剂量为2×10¹⁷ cm^-2)中观察到了室温铁磁性。所观察到的磁各向异性表明,氧离子注入的AlN薄膜中铁磁性是本征特性。在垂直于样品平面的外加磁场下,AlN:O_{（5×10）¹6}中的饱和磁化强度约为0.68 emu/g,高于AlN:O_{（2×10）¹7}中的饱和磁化强度0.09 emu/g。这是由于过高的氧离子剂量使得更多的氧离子占据相邻的Al离子位置,导致了反铁磁耦合的出现。正电子湮没多普勒展宽谱表明在氧离子注入的AlN薄膜中存在大量的Al空位。第一性原理计算表明氧离子注入的AlN薄膜中的铁磁性主要来源于Al空位,而高浓度的Al空位形成双空位或空位团将会使得AlN样品从铁磁性到反铁磁性转变,最终使样品的铁磁性减弱。更多还原

【Abstract】 Room-temperature ferromagnetism is observed in the O⁺-implanted AlN films with O⁺ doses of5×10¹⁶ cm^-2(AlN:O_{（5×10）¹6} and 2×10¹⁷ cm^-2(AlN:O_{（2×10）¹7}).The observed magnetic anisotropy indicates that the ferromagnetism is attributed to the intrinsic properties of O⁺-implanted AlN films.The out-of-plane saturation magnetization（M_S） of the AlN:O_{（5×10）¹6} is about 0.68 emu/g,much higher than that of AlN:O_{（2×10）¹7},0.09 emu/g,which is due to the excessively high O⁺ dose made more O⁺ ions occupy adjacent Al³⁺ positions in forms of antiferromagnetic coupling.Doppler broadening of positron annihilation radiation measurements demonstrate the existence of A1 vacancies in the O⁺-implanted AlN films.The first-principles calculations suggest that the ferromagnetism originates mainly from the Al vacancies.Meanwhile,the formation of divacancies or vacancy clusters by high concentrations of Al vacancies will lead to the transformation of V_Al-V_Al coupling from ferromagnetim to antiferromagnetism,ultimately weakening the ferromagnetism of the sample.更多还原