为了寻找新的高Tc的稀磁半导体(DMS),利用自旋局域密度泛函的第一性原理对 3d过渡金属(TM= V、Cr、Mn、Fe、Co或Ni)掺杂的II IV V2(CdGeP2 和ZnGeP2)以及I III VI2(CuGaS2 和CuGaSe2)黄铜矿半导体的电磁性质进行系统计算.结果发现:V或Cr...为了寻找新的高Tc的稀磁半导体(DMS),利用自旋局域密度泛函的第一性原理对 3d过渡金属(TM= V、Cr、Mn、Fe、Co或Ni)掺杂的II IV V2(CdGeP2 和ZnGeP2)以及I III VI2(CuGaS2 和CuGaSe2)黄铜矿半导体的电磁性质进行系统计算.结果发现:V或Cr 掺杂的 II IV V2 将出现铁磁(FM)状态,而 Mn、Fe或者 Co掺杂的 II IV V2 将出现反铁磁(AFM)状态,Ni掺杂时,DMS的磁性非常不稳定;在TM掺杂的 I III VI2 的DMS中,Cr、Mn掺杂的 CuGaS2 和 CuGaSe2将表现为FM状态,而当V、Fe、Co或Ni掺杂时,Cu(Ga,TM)S2 和Cu(Ga,TM)Se2 则表现了AFM性质.Cr掺杂的I IV V 以及 I III VI 黄铜矿半导体将可能出现较高的居里温度(Tc).展开更多
The crystallographic structures and magnetic properties of a Zn0.95Co0.05O thin film deposited on a C-sapphire substrate using a dual-beam pulsed laser deposition method were characterized. It was shown from crystallo...The crystallographic structures and magnetic properties of a Zn0.95Co0.05O thin film deposited on a C-sapphire substrate using a dual-beam pulsed laser deposition method were characterized. It was shown from crystallographic analysis that the film belongs to the wurtzite structure with the C-axis aligned with that of the substrate. Magnetic hysteresis loops were observed till up to room temperature. A small peak around 55 K was noticed on the magnetization vs. temperature curve. The corresponding temperature of the small peak is close to that of ‘the abnormal peak’ reported by X.M. Zhang et al. From the results obtained, no correlation was found between the abnormal peak and the quantum effects. The magnetic behaviors in the Zn0.95Co0.05O film cannot be explained by the ferromagnetism in diluted magnetic semiconductors. The magnetic mechanisms in ZnO-based diluted magnetic semiconductors are also discussed.展开更多
Unintentionally doped AIGaN layers, which were co.implanted with 400 keV Tb＋ ions and 200keV Cr＋ ions at doses of 1.5×1015cm-2, have been rapid thermally annealed at 800℃ and 900℃ for 5 min in flowing N2, Com...Unintentionally doped AIGaN layers, which were co.implanted with 400 keV Tb＋ ions and 200keV Cr＋ ions at doses of 1.5×1015cm-2, have been rapid thermally annealed at 800℃ and 900℃ for 5 min in flowing N2, Compared with Tb implanted AIGaN sample, the Tb and Cr co-implanted sample revesls a larger magnetic signal. In this work, the annealing effect on the structural and magnetic properties of Tb and Cr co-implanted AIGaN thin films have been studied. XRD and raman scattering results indicate that no second phase presents in thetin films and mast of the implantation induced defects can be removed by post-implantation annealing. Superconducting quantum interference device （SQUID） measurements show clear room temperature ferromagnetic behavior and an increase in the saturation magnetization as a result of annealing. The saturation magnetization of the 900℃ annealed sample is about 15 times higher than that of the 800℃ annealed sample.展开更多
文摘为了寻找新的高Tc的稀磁半导体(DMS),利用自旋局域密度泛函的第一性原理对 3d过渡金属(TM= V、Cr、Mn、Fe、Co或Ni)掺杂的II IV V2(CdGeP2 和ZnGeP2)以及I III VI2(CuGaS2 和CuGaSe2)黄铜矿半导体的电磁性质进行系统计算.结果发现:V或Cr 掺杂的 II IV V2 将出现铁磁(FM)状态,而 Mn、Fe或者 Co掺杂的 II IV V2 将出现反铁磁(AFM)状态,Ni掺杂时,DMS的磁性非常不稳定;在TM掺杂的 I III VI2 的DMS中,Cr、Mn掺杂的 CuGaS2 和 CuGaSe2将表现为FM状态,而当V、Fe、Co或Ni掺杂时,Cu(Ga,TM)S2 和Cu(Ga,TM)Se2 则表现了AFM性质.Cr掺杂的I IV V 以及 I III VI 黄铜矿半导体将可能出现较高的居里温度(Tc).
基金Supported by the Hangzhou Dianzi University Fund (Grant No. KYF091506003)funds from State Key Lab of Silicon Materials, Zhejiang University (Grant No. 2000603)
文摘The crystallographic structures and magnetic properties of a Zn0.95Co0.05O thin film deposited on a C-sapphire substrate using a dual-beam pulsed laser deposition method were characterized. It was shown from crystallographic analysis that the film belongs to the wurtzite structure with the C-axis aligned with that of the substrate. Magnetic hysteresis loops were observed till up to room temperature. A small peak around 55 K was noticed on the magnetization vs. temperature curve. The corresponding temperature of the small peak is close to that of ‘the abnormal peak’ reported by X.M. Zhang et al. From the results obtained, no correlation was found between the abnormal peak and the quantum effects. The magnetic behaviors in the Zn0.95Co0.05O film cannot be explained by the ferromagnetism in diluted magnetic semiconductors. The magnetic mechanisms in ZnO-based diluted magnetic semiconductors are also discussed.
文摘Unintentionally doped AIGaN layers, which were co.implanted with 400 keV Tb＋ ions and 200keV Cr＋ ions at doses of 1.5×1015cm-2, have been rapid thermally annealed at 800℃ and 900℃ for 5 min in flowing N2, Compared with Tb implanted AIGaN sample, the Tb and Cr co-implanted sample revesls a larger magnetic signal. In this work, the annealing effect on the structural and magnetic properties of Tb and Cr co-implanted AIGaN thin films have been studied. XRD and raman scattering results indicate that no second phase presents in thetin films and mast of the implantation induced defects can be removed by post-implantation annealing. Superconducting quantum interference device （SQUID） measurements show clear room temperature ferromagnetic behavior and an increase in the saturation magnetization as a result of annealing. The saturation magnetization of the 900℃ annealed sample is about 15 times higher than that of the 800℃ annealed sample.
