The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,...The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,theapplied magnetic field,and the temperature all affect the specific heat of these superlattices.For both the ferromagneticand ferrimagnetic superlattices,the specific heat decreases with increasing the spin quantum number,the absolutevalue of interlayer exchange coupling,intralayer exchange coupling,and anisotropy,while it increases with increasingtemperature at low temperatures.When an applied magnetic field is enhanced,the specific heat decreases in the two-layerferromagnetic superlattice,while it is almost unchanged in the two-layer ferrimagnetic superlattice at low fieldrange at low temperatures.展开更多
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
基金Supported by the Natural Science Foundation of Liaoning Province of China under Grant No.20062040
文摘The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,theapplied magnetic field,and the temperature all affect the specific heat of these superlattices.For both the ferromagneticand ferrimagnetic superlattices,the specific heat decreases with increasing the spin quantum number,the absolutevalue of interlayer exchange coupling,intralayer exchange coupling,and anisotropy,while it increases with increasingtemperature at low temperatures.When an applied magnetic field is enhanced,the specific heat decreases in the two-layerferromagnetic superlattice,while it is almost unchanged in the two-layer ferrimagnetic superlattice at low fieldrange at low temperatures.
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.
