Microfabrication and Magnetoelectric Properties of High-magnetoresistance Tunnel Junctions (論文特集号〔日本応用磁気学会〕第24回学術講演会)

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Spin-valve-type tunnel junctions with structure of Ta(5 nm)/Ni_<79>Fe_<21>(3 nm)/Cu(20 nm)/Ni_<79>Fe_<21>(3 nm)/Ir_<22>Mn_<78>(10 nm)/Co_<75>Fe_<25>(4 nm)/Al(0.80 nm)-oxide/Co_<75>Fe_<25>(4 nm)/Ni_<79>Fe_<21>(20 nm)/Ta(5 nm) were fabricated using a micro-fabrication technique. The optical lithography combined with Ar ion-beam etching and CF_4 active etching was used to pattern the junction area with the size from 100x100 down to 3x3 μm^2. A thinner barrier layer and a short plasma-oxidation time for Al-oxide layer were used in order to reduce the junction resistance and increase the TMR ratio. High TMR ratio of 69.1% at 4.2 K and 49.7% at room temperature were achieved. A spin-electron polarization tunneling model, based on magnon emission or absorption by the tunneling electrons during the tunnel process, was extended by defining an anisotropic wavelength cutoff energy of spin-wave in this work. Intrinsic magnetoelectric properties, such as the temperature dependence of TMR ratio and resistances from 4.2 to 300 K at 1.0 mV bias can be self-consistently evaluated using this extended model and a unique set of intrinsic parameters.
社団法人日本磁気学会の論文
2001-04-15