Single barrier magnetic-tunnel-junctions (MTJs) with the layer structure of Ta(5)/Cu(30)/Ta(5)/Ni79Fe21(5)/Ir22 Mn78(12)/Co60Fe20B20(4)/Al(0.8)-oxide/Co60Fe20B20(4)/Cu(30)/Ta(5) [thickness unit: nm] using the amorphou...Single barrier magnetic-tunnel-junctions (MTJs) with the layer structure of Ta(5)/Cu(30)/Ta(5)/Ni79Fe21(5)/Ir22 Mn78(12)/Co60Fe20B20(4)/Al(0.8)-oxide/Co60Fe20B20(4)/Cu(30)/Ta(5) [thickness unit: nm] using the amorphous Co60Fe20B20 alloy as free and pinned layers were micro-fabricated. The experimental investigations showed that the tunnel magnetoresistance (TMR) ratio and the resistance decrease with increasing dc bias voltage from 0 to 500 mV or with increasing temperature from 4.2 K to RT. A high TMR ratio of 86.2% at 4.2 K, which corresponds to the high spin polarization of Co60Fe20B20, 55%, was observed in the MTJs after annealing at 270℃ for 1 h. High TMR ratio of 53.1%, low junction resistance-area product RS of 3.56 kΩμm2, small coercivity HC of ≤4 Oe, and relatively large bias-voltage-at-half-maximum TMR with the value V1/2 of greater than 570 mV at RT have been achieved in such Co-Fe-B MTJs.展开更多
Nano-ring-type magnetic tunnel junctions(NR-MTJ)were nano-fabricated.The tunneling magnetoresistance(TMR)versus current(Ⅰ)loops of the NR-MTJs for a spin-polarized current switching were measured and the TMR ratio of...Nano-ring-type magnetic tunnel junctions(NR-MTJ)were nano-fabricated.The tunneling magnetoresistance(TMR)versus current(Ⅰ)loops of the NR-MTJs for a spin-polarized current switching were measured and the TMR ratio of around 20%～50% with a Al-O barrier at room temperature were observed.The critical value of switching current for the free Co_(60)Fe_(20)B_(20) layer between parallel and anti-parallel magnetization states is smaller than 650μA.The NR-MTJs arrays were also integrated above the transistors in ...展开更多
Magnetic, thermal and electrical properties of sputtered Co_(60)Fe_(20)B_(20) alloy films are investigated. An excellent linear relationship between the saturation magnetization per unit area and thickness is obtained...Magnetic, thermal and electrical properties of sputtered Co_(60)Fe_(20)B_(20) alloy films are investigated. An excellent linear relationship between the saturation magnetization per unit area and thickness is obtained in the as-deposited film with thickness ranging from 10 to 100 nm. For the as-deposited films a high effective saturation magnetization of 793.7 ± 42.9 emu cm_(-3) is derived from the fitting. An in-plane uniaxial magnetic anisotropy of ~10~4 erg cm^(-3)in magnitude is revealed by angular dependent magnetic measurements.A fourfold cubic magnetic anisotropy is found to develop with annealing, in line with the improvement of the crystalline structure in the film confirmed by X-ray diffraction measurements. Thermomagnetic measurements reveal a considerable variation of the saturation magnetization with temperature arising from the competition of the crystallization and the temperature dependent ferromagnetic behavior of the alloy film. Pronounced changes in electrical resistivity with temperature were observed in the alloy film,in accompany with the structural change. The activation barrier for crystallization was determined to be 1.43 eV from the electrical measurements with variable heating rates,showing a good thermal stability of the alloy film.展开更多
基金Project supported by the State Key Project of Fundamen-tal Research of Ministry of Science and Technology(MOST,China,Grant No.2001CB610601)Chinese Academy of Science.X.F.Han gratefully thanks the partial support of the National Natural Science Foundation of China(50271081 and 10274103)Distinct Young Researcher Foundation(50325104).
文摘Single barrier magnetic-tunnel-junctions (MTJs) with the layer structure of Ta(5)/Cu(30)/Ta(5)/Ni79Fe21(5)/Ir22 Mn78(12)/Co60Fe20B20(4)/Al(0.8)-oxide/Co60Fe20B20(4)/Cu(30)/Ta(5) [thickness unit: nm] using the amorphous Co60Fe20B20 alloy as free and pinned layers were micro-fabricated. The experimental investigations showed that the tunnel magnetoresistance (TMR) ratio and the resistance decrease with increasing dc bias voltage from 0 to 500 mV or with increasing temperature from 4.2 K to RT. A high TMR ratio of 86.2% at 4.2 K, which corresponds to the high spin polarization of Co60Fe20B20, 55%, was observed in the MTJs after annealing at 270℃ for 1 h. High TMR ratio of 53.1%, low junction resistance-area product RS of 3.56 kΩμm2, small coercivity HC of ≤4 Oe, and relatively large bias-voltage-at-half-maximum TMR with the value V1/2 of greater than 570 mV at RT have been achieved in such Co-Fe-B MTJs.
文摘Nano-ring-type magnetic tunnel junctions(NR-MTJ)were nano-fabricated.The tunneling magnetoresistance(TMR)versus current(Ⅰ)loops of the NR-MTJs for a spin-polarized current switching were measured and the TMR ratio of around 20%～50% with a Al-O barrier at room temperature were observed.The critical value of switching current for the free Co_(60)Fe_(20)B_(20) layer between parallel and anti-parallel magnetization states is smaller than 650μA.The NR-MTJs arrays were also integrated above the transistors in ...
基金supported by the Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University(ZQN-YX107)Research Start-up Funding for High-level Talents Project Sponsored by Huaqiao University(13BS401)
文摘Magnetic, thermal and electrical properties of sputtered Co_(60)Fe_(20)B_(20) alloy films are investigated. An excellent linear relationship between the saturation magnetization per unit area and thickness is obtained in the as-deposited film with thickness ranging from 10 to 100 nm. For the as-deposited films a high effective saturation magnetization of 793.7 ± 42.9 emu cm_(-3) is derived from the fitting. An in-plane uniaxial magnetic anisotropy of ~10~4 erg cm^(-3)in magnitude is revealed by angular dependent magnetic measurements.A fourfold cubic magnetic anisotropy is found to develop with annealing, in line with the improvement of the crystalline structure in the film confirmed by X-ray diffraction measurements. Thermomagnetic measurements reveal a considerable variation of the saturation magnetization with temperature arising from the competition of the crystallization and the temperature dependent ferromagnetic behavior of the alloy film. Pronounced changes in electrical resistivity with temperature were observed in the alloy film,in accompany with the structural change. The activation barrier for crystallization was determined to be 1.43 eV from the electrical measurements with variable heating rates,showing a good thermal stability of the alloy film.
