Fe/Al_2O_3/Fe隧道结的巨磁电阻效应

GIANT MAGNETORESISTANCE OF Fe/Al_2O_3/Fe TUNNELING JUNCTION

采用多靶离子束溅射镀膜技术制备了Fe(2 0 0℃退火 ) /Al2 O3/Fe多层膜隧道结样品 ,研究了隧道结样品的巨磁电阻效应 ,在室温下获得了 5.89%的巨磁电阻效应 ,具有甚高的低场灵敏度 并且测量了样品的伏安特性曲线 ,观察到了非线性的伏安特性曲线 。

A series of Fe/Al 2O 3/Fe tunneling junction samples were fabricated using ion beam sputtering technique. The base pressure of the vacuum chamber equipped with a Kauffman gun was 4.4×10 -4 Pa, and the argon (99.99%) pressure was 2.0×10 -2 Pa when sputtering. A Ag layer was first deposited onto the glass substrates. The first Fe layer was deposited at 200?℃ onto Ag film and annealed at the same temperature for about an hour. Then the Al layer was deposited and exposed to the air for more than 48 hours to be oxidized to Al 2O 3 layer at room temperature, and the second Fe layer was deposited at room temperature. The depositing rate was decreased to 2 nm/min by decreasing the Argon ion current. The coercive force of the two ferromagnetic layers was different. When applied magnetic field parallel to the film, the magnetization of the two ferromagnetic metal layers was first aligned anti parallel, then parallel. With applied magnetic field parallel to the film, a giant magnetoresistance of about 5.89% at room temperature was observed. The resistance of the junction samples increased sharply at about 60 Oe and decreased sharply at about 110 Oe, which showed a potential application of magnetic field sensors and read heads for hard disk drivers. A clear high resistance plateau was observed, which indicated that a perfect anti parallel state of both ferromagnetic metal electrodes was reached in this case. The V I character of the junction samples was studied, a nonlinear V I curve was observed and the tunneling junction was destroyed at about 500 mV, which demonstrated that the giant magnetoresistance of the tunneling junctions may originated from the spin dependant tunneling effect.