Reply to Correspondence on “Suppressing Energy Migration via Antiparallel Spin Alignment in One‐Dimensional Mn ²⁺ Halide Magnets with High Luminescence Efficiency”

Abstract To address concerns regarding the photoluminescence quantum yield (PLQY) or radiative rate ( k r ) of Cd 2+ doped (CH 3 ) 4 NMnCl 3 (TMMC:0.2Cd 2+ ), we conducted additional experiments on Cu impurity content, PLQY, and magneto‐optical spectra of both TMMC and TMMC:0.2Cd 2+ . Our results show that TMMC consistently exhibits a higher PLQY than TMMC:0.2Cd 2+ , even though TMMC contains trace Cu impurities, which typically act as luminescence‐quenching centers. The PLQY and k r values for TMMC:0.2Cd 2+ in our previous study may have been underestimated due to the susceptibility of halide samples and PLQY measurements to experimental conditions and the absence of a standardized measurement method. However, the predicted radiative rate ( k r = 1.12 × 10 3 s −1 ) for TMMC:0.2Cd 2+ , as derived from the pressure‐dependent model in the Correspondence, leads to an unphysical negative nonradiative rate ( k nr ) when considering the experimentally observed decay lifetime of 0.935 ms. This inconsistency renders the predicted data unconvincing, despite the theoretical validity of the model. Furthermore, the field‐dependent PL intensities and decay lifetimes of TMMC and TMMC:0.2Cd 2+ confirm that the antiparallel spin ordering of Mn 2+ ions plays a role similar to Cd 2+ in suppressing excitonic energy migration toward Cu 2+ trapping centers.