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We present a theoretical framework for understanding diffuse multiple scattering (DMS) in single crystals, focusing on diffuse scattering-Bragg (DS-Bragg) channels. These channels, when probed with high-flux, low-divergent monochromatic synchrotron X-rays, provide well-defined visualizations of Kossel lines. Our main contribution lies in modeling the intensity distribution along these lines by considering DS around individual reciprocal lattice nodes. The model incorporates contributions from both general DS and mosaicity, elucidating their connection to second-order scattering events. This comprehensive approach advances our understanding of DMS phenomena, enabling their use as probes for complex material behavior, particularly under extreme conditions., Comment: 8 pages, 8 figures, previously presented at MRS fall meeting 2023 (10.13140/RG.2.2.29836.08325)

Inducing a magnetic gap at the Dirac point of the topological surface state (TSS) in a 3D topological insulator (TI) is a route to dissipationless charge and spin currents. Ideally, magnetic order is present only at the surface and not in the bulk, e.g. through proximity of a ferromagnetic (FM) layer. However, such a proximity-induced Dirac mass gap has not been observed, likely due to insufficient overlap of TSS and the FM subsystem. Here, we take a different approach, namely FM extension, using a thin film of the 3D TI Bi$_2$Te$_3$, interfaced with a monolayer of the lattice-matched van der Waals ferromagnet MnBi$_2$Te$_4$. Robust 2D ferromagnetism with out-of-plane anisotropy and a critical temperature of $\text{T}_\text{c}\approx$~15 K is demonstrated by X-ray magnetic dichroism and electrical transport measurements. Using angle-resolved photoelectron spectroscopy, we observe the opening of a sizable magnetic gap in the 2D FM phase, while the surface remains gapless in the paramagnetic phase above T$_c$. This sizable gap indicates a relocation of the TSS to the FM ordered Mn moments near the surface, which leads to a large mutual overlap., Comment: 6 pages, 3 figures

Precise lattice parameter measurements in single crystals are achievable, in principle, by X-ray multiple diffraction (MD) experiments. Tiny sample misalignments can compromise systematic usage of MD in studies where accuracy is an important issue. In this work, theoretical treatment and experimental methods for correcting residual misalignment errors are presented and applied to probe the induced strain of buried InAs quantum dots on GaAs (001) substrates., Comment: To be presented at the 5th Low Dimensional Structure and Devices, Cancun, Mexico, 12-17 December 2004. 4 pages, 4 figures

Ultra-precise lattice parameter measurements in single crystals are achievable, in principle, by X-ray multiple diffraction (XMD) experiments. Tiny sample misalignments have hindered the systematic usage of XMD in studies where accuracy is an important issue. In this work, theoretical basement and methods for correcting general misalignment errors are presented. As a practical demonstration, the induced strain of buried InAs quantum dots grown on GaAs (001) substrates is determined. Such a demonstration confirms the possibility to investigate epitaxial nanostructures via the strain field that they generate in the substrate crystalline lattice. This work was supported by the Brazilian founding agencies FAPESP (grant numbers 02/10185-3 and 02/10387-5), CNPq (proc. number 301617/95-3 and 150144/03-2) and LNLS (under proposal number D12A-XRD1 2490/03)., Comment: pdf format - 6 pages including 5 figures and 1 table Keywords: X-ray diffraction, semiconductors, nanomaterials, quantum dots Submitted to publication in Physical Review B