Impact of buffer layer and Pt thickness on the interface structure and magnetic properties in (Co/Pt) multilayers
M Bersweiler1, K Dumesnil1, D Lacour1
1Institut Jean Lamour (UMR CNRS 7198), Université de Lorraine, B.P. 70239, Vandoeuvre-lès-Nancy F-54506, France.
Summary
Interface engineering in cobalt-platinum multilayers significantly impacts magnetic properties. Thicker platinum layers and rougher interfaces enhance perpendicular magnetic anisotropy (PMA), crucial for advanced magnetic storage technologies.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Cobalt-platinum (Co/Pt) multilayers are key materials for magnetic storage devices.
- Perpendicular magnetic anisotropy (PMA) is essential for high-density data storage.
- Interface properties significantly influence the magnetic behavior of thin films.
Purpose of the Study:
- To investigate the effect of platinum (Pt) layer thickness on the interface structure and magnetic properties of (Co/Pt) multilayers.
- To understand how buffer layers (Pt vs. oxides like MgO or AlOx) affect the magnetic anisotropy.
- To elucidate the relationship between interface roughness, intermixing, and magnetic anisotropy.
Main Methods:
- Sputtering deposition of (Co/Pt) multilayers on different buffer layers (Pt, MgO, AlOx).
- Systematic variation of Pt layer thickness (1.2 nm–2.2 nm).
- Analysis of interface structure (roughness and intermixing) and magnetic properties (effective anisotropy, saturation magnetization).
Main Results:
- Increasing Pt thickness leads to sharper interfaces and enhanced effective anisotropy.
- PMA is achieved on oxide buffers but with lower effective anisotropy due to more perturbed interfaces.
- Enhanced saturation magnetization (Ms) is observed for rough/intermixed interfaces, attributed to Pt-induced polarization.
- Volume dipolar anisotropy is the primary factor reducing effective anisotropy (Keff) in systems grown on oxides.
- A supplemental positive contribution, consistent with dipolar surface anisotropy, promotes PMA for rough interfaces and high Ms.
Conclusions:
- Interface quality and buffer layer choice critically determine the PMA in (Co/Pt) multilayers.
- Rougher interfaces, despite potentially lower effective anisotropy, can exhibit enhanced overall anisotropy due to competing surface and volume effects.
- These findings offer insights for designing advanced magnetic materials with tailored properties for spintronic applications.
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