2006 年 30 巻 3 号 p. 366-369
Polycrystalline and single crystalline thin films of Co2(Cr1-xFex)Al (x = 0.6, 1) full-Heusler alloys with different disordering were prepared on thermally oxidized Si and MgO(001) substrates, respectively, by the dc magnetron sputtering method. The magnetic tunnel junctions with a polycrystalline and single crystalline B2 type Co2FeAl (x =1) electrode demonstrate TMR of 70% and 75% at 5 K, respectively, which is larger than that of 65% at 5 K for Co75Fe25, indicating that the spin polarization for Co2FeAl is larger than that for Co75Fe25. The TMR for Co2FeAl with both the A2 and the B2, which is controlled by substrate heating, is almost the same, whereas for Co2(Cr0.4Fe0.6)Al the TMR increases with increasing the degree of ordering, corresponding to the first-principles calculations.