2006 年 30 巻 4 号 p. 455-458
We have investigated that the structural and magnetic properties of Co2CrGa full-Heusler alloy films and researched the tunnel magnetoresistance (TMR) in magnetic tunnel junctions (MTJs) using a Co2CrGa electrode on a MgO(100) substrate. Co2CrGa films were fabricated with substrate heating (RT ≤ Ts ≤ 500°C) or post-annealing (RT ≤ Ta ≤ 500°C) after the deposition using an ultrahigh vacuum dc magnetron sputtering system. L21-ordered Co2CrGa thin films were obtained at Ts ≥ 300°C or Ta ≥ 200°C. The maximum magnetic moment per formula unit measured at 5 K were 2.8 μB and 2.6 μB for TS and Ta = 400°C, respectively, which are over 85% of the theoretical value. The maximum TMR of 18% at RT and 42% at 5 K are obtained for the MTJ using the L21-structured Co2CrGa film as a bottom electrode. It is expected that the TMR can be enhanced by optimizing the interface of Co2CrGa/AlOx.