Co-sputtered PtMnSb thin films and PtMnSb/Pt bilayers for spin-orbit torque investigations

TL;DR

This study reports on the growth, structural properties, and epitaxial quality of PtMnSb thin films and PtMnSb/Pt bilayers, highlighting their potential for spin-orbit torque applications in magnetic memory devices.

Contribution

It presents the first detailed epitaxial growth and characterization of PtMnSb thin films and bilayers, emphasizing their structural phases and interface quality for spintronics.

Findings

Thin PtMnSb films are monocrystalline with (001) orientation.

Thicker films grow layer-by-layer with high-quality interfaces.

Pt grows epitaxially on PtMnSb without significant interdiffusion.

Abstract

The manipulation of the magnetization by spin-orbit torques (SOTs) has recently been extensively studied due to its potential for efficiently writing information in magnetic memories. Particular attention is paid to non-centrosymmetric systems with space inversion asymmetry, where SOTs emerge even in single-layer materials. The half-metallic half-Heusler PtMnSb is an interesting candidate for studies of this intrinsic SOT. Here, we report on the growth and epitaxial properties of PtMnSb thin films and PtMnSb/Pt bilayers deposited on MgO(001) substrates by dc magnetron co-sputtering at high temperature in ultra-high vacuum. The film properties were investigated by x-ray diffraction, x-ray reflectivity, atomic force microscopy, and electron microscopy. Thin PtMnSb films present a monocrystalline C1b phase with (001) orientation, coexisting at increasing thickness with a polycrystalline phase with (111) texture. Films thinner than about 5 nm grow in islands, whereas thicker films grow layer-by-layer, forming a perfect MgO/PtMnSb interface. The thin PtMnSb/Pt bilayers also show island growth and a defective transition zone, while thicker films grow layer-by-layer and Pt grows epitaxially on the half-Heusler compound without significant interdiffusion.