Fabrication of (001) Oriented TMR Film With Highly Ordered $L1_{0}$ -Fe(Pd,Pt) Alloy Films by Using a Very Thin Fe Underlayer

Magnetic tunnel junctions with L1₀ -FePd storage layer which has low perpendicular magnetic anisotropy and lower ordering temperature compared with the case of L1₀-FePt films were fabricated with using a very thin Fe underlayer. The main results are as follows. 1) The long-range chemical order degree and the full width at half maximum of diffraction peak rocking curve for the FePd(002) for the L1₀-FePd film with a very thin Fe underlayer onto MgO(100) substrate were more than 0.9 and less than 2.0°. 2) The perpendicular coercive force and magnetic anisotropy field for the L1₀-FePd film with the very thin Fe underlayer were 300 Oe and 15 kOe. 3) The full width at half maximum of diffraction peak rocking curve for the Fe(Pd,Pt)(002) for the FePt/MgO/FePd film with a very thin Fe underlayer onto MgO(100) substrate was less than 2.0°. 4) The out-of-film-plane hysteresis loop of the FePt/MgO/FePd film with the very thin Fe underlayer shows a clear antiparallel state at the magnetic field from 500 to 1000 Oe between FePt reference layer and FePd storage layer. It is found that the very thin Fe underlayer is effective to obtain the FePt/MgO/FePd film with highly (001) orientation and highly L1₀ ordered structure.