Enhancing perpendicular magnetic anisotropy and magneto-optical signal of electron beam evaporated [Co/Pt]1 and [Co/Pt]2 thin films

Nanostructured magnetic multilayers with perpendicular magnetic anisotropy (PMA) are interesting materials for a plethora of magneto-optical and spintronic applications. The search for PMA in these heterostructures is commonly pursued by employing magnetron sputtering under ultra-high vacuum conditions and stacking a large number of layer repetitions. This work introduces a straightforward approach for Co/Pt ultra-thin film growth using electron beam evaporation under lower demanding vacuum conditions—i.e., base pressures around 10−6 mbar—achieving a high degree of PMA and tunable magnetic properties with only one repetition of the magnetic material. The non-conformal deposition geometry of this technique ensures compatibility with micro- and nanofabrication. A Cu buffer layer promotes strong PMA, as it enhances the (111) texture growth of the Co/Pt stack under high vacuum conditions. The control of the Cu and Pt thicknesses allows to fine-tune coercivities across a wide range of magnetic fields while maintaining a well-defined out-of-plane loop squareness and a sharp transition between the two perpendicular states. The influence of the Cu layer on the magneto-optical signal reveals a trade-off between the increase in coercivity and the reduction of the magneto-optical signal as the Cu buffer layer grows. Adding a second Co/Pt repetition mitigates this limitation, yielding samples with both strong magneto-optical signals and high coercivities, featuring the largest effective anisotropy.