Electric field-controlled magnetization in bilayered magnetic films for magnetoelectric memory
Mark Rainforth, W.
- Publisher: American Institute of Physics (AIP)
Bilayered magnetic films (Co<inf>50</inf>Fe<inf>50</inf> (CoFe)/Metglas) were RF sputtered on both (001)-oriented and (011)-oriented PMN-PT (lead magnesium niobate-lead titanate) substrates. Electric field-controlled magnetization changes were observed in all these samples: 65 nm CoFe/24 nm Metglas/(001) PMN-PT, 65 nm CoFe/24 nm Metglas/(011) PMN-PT, and 30 nm CoFe/12 nm Metglas/(011) PMN-PT. The maximum magnetic remanence ratio change (ΔM<inf>r</inf>/M<inf>s</inf>) was 46% for CoFe/Metglas/(001) PMN-PT. In this heterostructure, the electric-field created two new non-volatile switchable remanence states and the as-grown remanence state was altered permanently. High-resolution transmission electron microscopy images show a sharp and smooth interface between Metglas and substrate and conversely a rougher interface was observed between Metglas and CoFe films. In the 30 nm CoFe/12 nm Metglas/(011) PMN-PT sample, a large ΔM<inf>r</inf>/M<inf>s</inf> of 80% along the  direction was measured, while the ΔM<inf>r</inf>/M<inf>s</inf> along the [01-1] direction was 60% at the applied electric field of 5 kV/cm, corresponding to a giant magnetoelectric coupling constant α = μ<inf>o</inf>ΔM<inf>r</inf>/E = 2.9 × 10<sup>-6</sup> s/m.