MgO基板上に作製したCo_2V_<0.67>Fe_<0.33>Al薄膜の構造と磁性およびトンネル磁気抵抗(薄膜)

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Co_2V_<0.67>Fe_<0.33>Al full-Heulser alloy films were fabricated on an MgO (100) single crystalline substrate by using two different heat treatments-substrate heating and post-annealing. Ultra-high-vacuum dc magnetron sputtering was used to prepare the sample. The L2_1 structure was obtained when the substrate temperature (T_s) was 500℃. For the same sample, the magnetic moment per formula unit showed the highest value of 2.4μB at 5K. There were small differences between the samples fabricated by substrate heating and post-annealing in terms of their structural and magnetic properties. A magnetic tunnel junction (MTJ) using Co_2V_<0.67>Fe_<0.33>Al as a bottom electrode was fabricated. A larger tunnel magnetoresistance (TMR) was obtained by substrate heating than post-annealing with a maximum value of 28% at RT and 50% at 5K when the Co_2V_<0.67>Fe_<0.33>Al was sputtered at T_s=500℃. We found that there is an intimate relationship between the lattice constant of Co_2V_<0.67>Fe_<0.33>Al and the TMR.
2006-05-01