Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers....Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers. The selection criteria are square magnetic hysteresis loops, weaker current shunting effect, and proper coercivity. The optimal reference layer and free layer are Pt（5.0 nm）/[Co（0.4 nm）/Pt（0.6 nm）]3/Co（0.4 nm）/Cu（3.0 nm）and Cu（3.0 nm）/[Co（0.4 nm）/Pt（1.5 nm）]4, respectively.The resulting pseudo SV exhibits two well-separated hysteresis loops when the field is applied perpendicular to the film plane. The minor hysteresis loop corresponding to the free layer shifts toward negative direction of the magnetic field axis, indicating ferromagnetic interlayer exchange coupling between the two magnetic layers. The coupling also enhances the coercivity（HC） of both layers. The perpendicular giant magnetoresistance（GMR） of 2.7 % is achieved with current in plane measurement. The GMR first increases when Pt seed layer is thickened, reaches a maximum of 3.0 % at 4 nm and then decreases with the further increase of thickness. But thicker Cu spacer layer always lowers the GMR of the SV.展开更多
The effect of ultrathin Fe layer on perpendicular magnetic anisotropy(PMA) in magnetron-sputtered Co/Pt multilayers was investigated by magnetic measurements.Magnetization hysteresis(M-H) loops and microstructures of ...The effect of ultrathin Fe layer on perpendicular magnetic anisotropy(PMA) in magnetron-sputtered Co/Pt multilayers was investigated by magnetic measurements.Magnetization hysteresis(M-H) loops and microstructures of the samples were measured by vibrating sample magnetometer(VSM) and X-ray diffraction(XRD) and highresolution transmission electron microscopy(HRTEM),respectively.It is found that the PMA is strongly dependent on the interface where Fe layer was doped.When Fe layer was doped at Co/Pt interface where Pt was deposited on Co,the PMA decreases monotonically with Fe layer thickness(tFe) increasing.However,when Fe layer was doped at Pt/Co interface where Co was deposited on Pt,the PMA shows a peak at t_(Fe)=0.1 nm.It is considered that the PMA variation is mainly due to the tuning in the electron occupation states of 3 d orbits at Fe-doped Pt/Co interface.Furthermore,the annealing stability of PMA can also be improved when Fe layer was doped at Pt/Co interface.HRTEM results demonstrate that the magnetic anisotropy evolution is mainly caused by anneal-induced interdiffusion.展开更多
NOx storage and reduction(NSR)technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NOx)from lean-burn engines,and the potential of the plasma catalysis method for NOx r...NOx storage and reduction(NSR)technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NOx)from lean-burn engines,and the potential of the plasma catalysis method for NOx reduction has been confirmed in the past few decades.This work reports the NSR of nitric oxide(NO)by combining non-thermal plasma(NTP)and Co/Pt/Ba/γ-Al2O3(Co/PBA)catalyst using methane as a reductant.The experimental results reveal that the NOx conversion of NSR assisted by NTP is notably enhanced compared to the catalytic efficiency obtained from NSR in the range of 150°C–350°C,and NOx conversion of the 8%Co/PBA catalyst reaches 96.8%at 350°C.Oxygen(O_(2))has a significant effect on the removal of NOx,and the NOx conversion increases firstly and then decreases when the O_(2)concentration ranges from 2%to 10%.Water vapor reduces the NOx storage capacity of Co/PBA catalysts on account of the competition for adsorption sites on the surface of Co/PBA catalysts.There is a negative correlation between sulfur dioxide(SO_(2))and NOx conversion in the NTP system,and the 8%Co/PBA catalyst exhibits higher NOx conversion compared to other catalysts,which shows that Co has a certain SO_(2)resistance.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 11174020, 51331002, and 51371027)the Fundamental Research Funds for the Central Universities FRF-SD-12-011A
文摘Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers. The selection criteria are square magnetic hysteresis loops, weaker current shunting effect, and proper coercivity. The optimal reference layer and free layer are Pt（5.0 nm）/[Co（0.4 nm）/Pt（0.6 nm）]3/Co（0.4 nm）/Cu（3.0 nm）and Cu（3.0 nm）/[Co（0.4 nm）/Pt（1.5 nm）]4, respectively.The resulting pseudo SV exhibits two well-separated hysteresis loops when the field is applied perpendicular to the film plane. The minor hysteresis loop corresponding to the free layer shifts toward negative direction of the magnetic field axis, indicating ferromagnetic interlayer exchange coupling between the two magnetic layers. The coupling also enhances the coercivity（HC） of both layers. The perpendicular giant magnetoresistance（GMR） of 2.7 % is achieved with current in plane measurement. The GMR first increases when Pt seed layer is thickened, reaches a maximum of 3.0 % at 4 nm and then decreases with the further increase of thickness. But thicker Cu spacer layer always lowers the GMR of the SV.
基金financially supported by the National Natural Science Foundation of China (Nos.51371027 and 51331002)the National Key Scientific Research Projects of China (No.2015CB921502)the Ph.D.Programs Foundation of Ministry of Education (No.20120006130002)。
文摘The effect of ultrathin Fe layer on perpendicular magnetic anisotropy(PMA) in magnetron-sputtered Co/Pt multilayers was investigated by magnetic measurements.Magnetization hysteresis(M-H) loops and microstructures of the samples were measured by vibrating sample magnetometer(VSM) and X-ray diffraction(XRD) and highresolution transmission electron microscopy(HRTEM),respectively.It is found that the PMA is strongly dependent on the interface where Fe layer was doped.When Fe layer was doped at Co/Pt interface where Pt was deposited on Co,the PMA decreases monotonically with Fe layer thickness(tFe) increasing.However,when Fe layer was doped at Pt/Co interface where Co was deposited on Pt,the PMA shows a peak at t_(Fe)=0.1 nm.It is considered that the PMA variation is mainly due to the tuning in the electron occupation states of 3 d orbits at Fe-doped Pt/Co interface.Furthermore,the annealing stability of PMA can also be improved when Fe layer was doped at Pt/Co interface.HRTEM results demonstrate that the magnetic anisotropy evolution is mainly caused by anneal-induced interdiffusion.
基金by the National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2019A13)the National Key Research and Development Project of China(No.2019YFC1805505)+2 种基金the Shanxi Province Bidding Project(No.20191101007)the Major Science and Technology Projects of Shanxi Province(No.20181102017)State Key Laboratory of Organic Geochemistry(No.SKLOG-201909)。
文摘NOx storage and reduction(NSR)technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NOx)from lean-burn engines,and the potential of the plasma catalysis method for NOx reduction has been confirmed in the past few decades.This work reports the NSR of nitric oxide(NO)by combining non-thermal plasma(NTP)and Co/Pt/Ba/γ-Al2O3(Co/PBA)catalyst using methane as a reductant.The experimental results reveal that the NOx conversion of NSR assisted by NTP is notably enhanced compared to the catalytic efficiency obtained from NSR in the range of 150°C–350°C,and NOx conversion of the 8%Co/PBA catalyst reaches 96.8%at 350°C.Oxygen(O_(2))has a significant effect on the removal of NOx,and the NOx conversion increases firstly and then decreases when the O_(2)concentration ranges from 2%to 10%.Water vapor reduces the NOx storage capacity of Co/PBA catalysts on account of the competition for adsorption sites on the surface of Co/PBA catalysts.There is a negative correlation between sulfur dioxide(SO_(2))and NOx conversion in the NTP system,and the 8%Co/PBA catalyst exhibits higher NOx conversion compared to other catalysts,which shows that Co has a certain SO_(2)resistance.
