Laser-induced demagnetization in a MAX phase (Cr0.5Mn0.5)2GaC

Referee: [Abstract and §3] Abstract and §3 (demagnetization transients): the assertion that the observed two-step form is 'a signature of two-dimensional magnetic systems' is load-bearing for the headline claim but rests on an untested uniqueness assumption. The 40 nm thickness corresponds to dozens of M2X layers; no controls, thickness series, or comparisons to 3D-ordered analogs are presented to exclude inhomogeneous heating, multi-domain relaxation, or magnon-phonon channels that could produce similar fast-then-slow profiles in a layered but still 3D-ordered material below 250 K.

Authors: We agree that the 40 nm film thickness corresponds to multiple M2X layers and that no thickness series or direct 3D-analog comparisons are included, so uniqueness to strictly 2D magnetism cannot be rigorously proven from the present data alone. The interpretation draws from the established association of two-step type-II transients with reduced-dimensional magnetism in the literature, but we will revise the abstract and §3 to describe the behavior as 'consistent with' or 'reminiscent of' two-dimensional systems rather than a definitive signature. We will also add a dedicated paragraph discussing possible alternative mechanisms, including inhomogeneous heating, multi-domain relaxation, and magnon-phonon channels, while noting that the epitaxial quality and sharp magnetic ordering below 250 K make such effects less likely to dominate. This addresses the concern without requiring new experiments. revision: partial

Referee: [§4] §4 (three-temperature model fits): the reconstruction of C_s(T) and the conclusion of its weak temperature dependence are central to explaining the absence of fluence/temperature slowing, yet no raw transients, error bars, specific fluence values, or fit-quality metrics (e.g., reduced χ² or parameter covariance) are shown. Without these, it is impossible to assess whether the extracted G_es, G_sl, and C_s are uniquely constrained or affected by fitting degeneracy between C_s and the spin-lattice coupling.

Authors: We acknowledge that additional details on the fitting procedure are needed for full assessment. In the revised manuscript we will move the raw demagnetization transients to the supplementary information, explicitly list the fluences employed, include error bars on the extracted parameters, and report fit-quality metrics including reduced χ² values and covariance matrices. We will also add a short discussion of parameter degeneracy, explaining how the weak C_s(T) dependence remains robust when G_sl is varied within physically reasonable bounds. revision: yes

Referee: [§4] §4, Eq. (model equations): the three-temperature model is applied without material-specific corrections for the nanolaminated structure or possible additional relaxation channels. The paper does not demonstrate that the fitted parameters remain stable under reasonable variations in the assumed functional forms for C_e(T) or C_l(T), which directly impacts the claimed weak C_s(T) dependence.

Authors: The three-temperature model is applied in its standard phenomenological form, which has been successfully used for other metallic layered magnets. To address the referee's point, the revised §4 will include a sensitivity analysis demonstrating that the extracted weak temperature dependence of C_s(T) persists when the functional forms of C_e(T) and C_l(T) are varied within literature ranges for similar metals. We will also add a brief discussion of why nanolamination-specific corrections or extra channels are not required to describe the data, based on the quality of the fits and the absence of additional features in the transients. revision: partial