使用电子束蒸发镀膜方法在覆有掩膜板的SiO2/Si基片上制备了Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20结构平面自旋阀,研究了不同退火温度对Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20平面自旋阀中自旋积累的影响。使用非局域测量方法分别测量制备态以及300,400和500℃不同退火温度下Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20平面自旋阀中Ag层中自旋积累信号的大小。实验结果表明:自旋积累信号在制备态下为1.3 mΩ;随着退火温度的升高,自旋积累信号也随着增大,并在500℃退火30 min后达到极大值(~14.5 mΩ),比制备态提高了一个数量级;进一步提高退火温度到600℃时,由于Ag层会凝聚成岛状结构而破坏Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20平面自旋阀中Ag层的连续性,使Ag层断裂,从而使测量到的自旋积累信号为0 mΩ。研究认为,Ni80 Fe20/Al2 O3/Ag/Al2 O3/Ni80 Fe20平面自旋阀中自旋积累信号的增强主要是高的界面自旋极化率以及长的自旋扩散长度共同作用的结果。Ni80 Fe20/Al2O3/Ag/Al2O3/Ni80 Fe20平面自旋阀中的铁磁/非磁金属界面处Al2 O3插层的平整度在退火后得到改善,有效地提高了界面自旋极化率;同时,样品表面的Al2 O3保护层退火后对Ag层中自旋电子的散射作用的增强,提高了Ag中自旋电子的扩散长度。
Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20 lateral spin valves were prepared on SiO2/Si substrate with shadow resistor by e-beam evaporation.The effect of annealing on the spin accumulation in Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20 lateral spin valves was investigated.The nonlocal measurement was used to detect the spin accumulation signal in Ag wire of the Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20 lateral spin valves for samples as-deposited and after 300,400,500 ℃ annealing.The results showed that the spin accumulation signal was 1.3 mΩ for the as-deposit sample.Then the spin accumulation signal increased with increasing the annealing temperature,and reached the maximal valve ~14.5 mΩ after annealing at 500 ℃ for 30 min,this value was ten times larger than that of as-deposit sample.Further increase of the annealing temperature up to 600 ℃ made the Ag wire agglomerate and destroyed the Ag wire of the Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20 lateral spin valves,make the spin accumulation signal decrease to 0 mΩ.The analysis indicated that the enhancement of the spin accumulation signal in Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20 lateral spin valves maybe attributed to the higher interfacial spin polarization and longer spin diffusion length in Ag wire.The high interfacial spin polarization of the Ni80Fe20/Al2O3/Ag/Al2O3/Ni80Fe20 lateral spin valves mainly attributed to the smoother Al2O3 inserted layer after annealing;and the longer spin diffusion length mainly attribute to the Al2O3 capping layer which decreased the spin scattering rate after annealing.