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

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 ultimately 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.

Advanced data analysis procedure for hard x-ray resonant magnetic reflectivity discussed for Pt thin film samples of various complexity

“…The epitaxial Pt/Fe//MgO(001) bilayer and TaO x /MgO/Ta/Co/Pt//SiO x /Si(001) multilayer were deposited at room temperature. In contrast, the PtMnSb thin films were prepared at high temperatures to achieve optimal growth without utilizing any seed layer [32] and were in situ capped with either AlO x /MgO or Pt. The theoretical and experimental details regarding the XRMR measurements and beamline specifications can be found in appendix A.…”

“…In case of the Pt/Fe bilayer, the off-resonant XRR measurements 100 eV below the Pt absorption edge were used to determine the correct structural properties which were in turn used to derive the optical constants at the resonance energy. Here, each element is assumed to have a homogeneous layer density based on the epitaxial growth [32] as well as a finite interface roughness which are determined far from the absorption edge. This procedure detailed by Klewe et al [22] is only applicable for simple and well-defined systems that are easy to model with high accuracy (e.g.…”

“…The detailed analysis of a second system, in which Pt is an integral part of a complex multilayer made of a single Pt layer adjacent to a Co layer that induces MPE, is discussed in appendix C [30,31]. The third example is a PtMnSb thin film, a half-metallic Heusler compound, which is an interesting candidate for studies of intrinsic spin-orbit torques [32], with and without a single Pt layer on top.…”

Spin-orbit torques in strained PtMnSb from first principles

“…Its half-metallicity has been established both experimentally and theoretically. It can be grown epitaxially on MgO(001) [19] and on W(001)/MnO(001) [20]. It exhibits a giant magneto-optical Kerr effect [21,22], which makes it attractive for magneto-optical recording.…”

Optimization of half-Heusler PtMnSb alloy films for spintronic device applications

“…PtMnSb, as a kind of half-Heusler alloys, was reported to have a half-metallic band structure [10] and a large magneticoptical Kerr effect [12][13][14][15][16][17]. In the previous studies, the bulk specimen of PtMnSb alloys [12,13] and PtMnSb films on glass or Al 2 O 3 (0 0 0 1) substrates [14,15], as well as tungstenbuffered MgO(0 0 1) substrates [16] were prepared for investigating magneto-optical properties.…”