Depth sensitive X‐ray diffraction as a probe of buried half‐metallic inclusions

Abstract

The ferromagnetic material MnSb can exist in two polymorphs in epitaxial thin‐film form, namely niccolite n‐MnSb and cubic c‐MnSb. We investigate the behavior of these polymorphs using grazing incidence depth‐dependent in‐plane X‐ray diffraction. The in‐plane lattice parameter evolution of a nominal 3000 Å thin film reveals a small near‐surface compression of ∼0.1% in the majority n‐MnSb component. A similar effect is also observed for the cubic polymorph, suggesting that the local strain environment of these crystallites is dominated by the n‐MnSb matrix. Collated in‐plane X‐ray diffraction data from a GaAs/ normalIn0.5normalGa0.5As(111)/MnSb heterostructure in the near‐surface region with probing depths ranging between 20 and 450 Å. Present are two of the polymorphs of MnSb: the niccolite (n‐) and cubic zincblende (c‐) phases.

Hybrid Heteroepitaxial Growth Mode

“…Figure shows grazing incidence (in‐plane) XRD data with Q aligned along the GaAs[] direction. Reflections from the Sb cap, MnSb epilayer and GaAs substrate are all present; the latter has much lower relative intensity that in the out‐of‐plane case due to the increased surface specificity of the grazing incidence measurement . With decreasing film thickness, we observe a shift in the MnSb() reflection toward the GaAs() reflection position.…”

Geometry of X‐ray based measurement of residual strain at desired penetration depth

“…Using Eqs. (16)(17)(18) and Eqs. (5,6,11) for the components of n, one can get the instrumental angles Ω, χ, and φ explicitly expressed via ψ, ϕ, and μτ.…”

“…Based on Eqs. (16)(17)(18) and (14), it is easy to link (ψ, η, ϕ) to (Ω, χ, φ). With ψ, |Ω| and |χ| in the range from 0 to π/2, the goniometer angles are given by Ω = arctan (tan ψ cos η)…”

“…Then there is the issue of the instrumental angle φ. Equation (18) implies that tan(φ − ϕ) = sin χ cot Ω. To calculate φ, Kumar et al [10] use the related formula φ = ϕ + arctan (sin χ cot Ω), which gives only angles φ differing from ϕ by less than π/2, and it fails to give solutions for which |φ − ϕ| exceeds π/2.…”

“…For simplicity, only the case of compact (bulk) solids with constant attenuation coefficient μ was considered, but a number of observations contained in this paper can be used in the more complicated problem of layered materials, with z-dependent μ. The subject of controlling the penetration depth is also essential in the large and complex field of grazingincidence X-ray diffraction with its broad applications in surface-and thin-film studies (e.g., [18,19]). Finally, the presented results are also relevant for the geometrically similar technique of determining near-surface crystallographic textures [20][21][22].…”