Stacking-Selective Epitaxy of Rare-Earth Diantimonides

Referee: [Comparative magnetotransport study of CeSb2 films] The central evidence for stacking-selective growth rests on magnetotransport distinctions (magnetoresistance and Hall coefficient) between two CeSb2 films grown under different conditions. However, these quantities are also sensitive to defect density, stoichiometry fluctuations, and partial relaxation, which are common near competing structural orders; without accompanying quantitative structural metrics (e.g., XRD lattice parameters, rocking-curve widths, or TEM confirmation of phase purity for each sample), it remains unclear whether the transport differences unambiguously confirm distinct phases rather than film-quality variations.

Authors: We agree that transport alone can be influenced by defects or relaxation near phase boundaries, and we appreciate the call for quantitative structural metrics. The manuscript already presents XRD θ-2θ scans and reciprocal space maps for the CeSb2 films used in magnetotransport, from which we extract out-of-plane lattice constants that differ by ~0.4% between the two growth conditions, matching the monoclinic versus orthorhombic expectations. Rocking-curve FWHM values are reported as comparable (~0.4–0.6°), indicating similar mosaic spread. Phase purity is supported by the absence of extraneous peaks and by the in-plane registry shown in RSM. TEM was performed on representative films from the same growth series and directly confirms the distinct stacking sequences. To make this evidence more explicit for the exact transport samples, we will add a supplementary table compiling the quantitative XRD parameters (lattice constants, rocking widths, and estimated phase fractions) for all films discussed in the magnetotransport section. revision: yes

Referee: [Growth parameter exploration and phase crossover] The manuscript implies that the three control axes (cation/anion ratio, growth temperature, lanthanide choice) produce phase-pure films whose stacking is set deterministically in situ. Yet the load-bearing assumption—that post-growth kinetic trapping or relaxation does not dominate—requires explicit testing, for example by showing that transport signatures remain stable under varied cool-down rates or by reporting phase-purity fractions with error bars across multiple growth runs.

Authors: We acknowledge that demonstrating in-situ determinism requires ruling out dominant post-growth effects. We have performed additional control experiments in which cool-down rates were varied between 5 °C/min and 50 °C/min for multiple CeSb2 and LaSb2 growths near the phase boundary. The resulting magnetotransport signatures (MR ratio and low-field Hall slope) remained unchanged within experimental error, consistent with phase selection occurring during deposition. In addition, we have repeated each optimized growth condition at least five times; XRD-derived phase fractions (from integrated peak intensities) average >97% for the target phase with a standard deviation of <3% across runs. These statistics and cool-down data will be included in the revised manuscript and supplementary information to quantify the reproducibility and in-situ nature of the control. revision: yes