Channel-resolved excitation trends in Si, GaAs, and NiO for sub-GeV dark matter detection

The direct detection of sub-GeV dark matter requires target systems capable of converting very small deposited energies into observable low-energy excitations. In this work, we develop a phenomenological comparative framework for examining electronic, phononic, and magnonic response trends in three representative condensed-matter targets: silicon (Si), gallium arsenide (GaAs), and nickel oxide (NiO). The purpose of the framework is not to provide an ab initio prediction of absolute event rates, but to compare how material-specific excitation scales and effective channel weights influence the relative response under a common set of dark matter assumptions. The total response is decomposed into channel-resolved contributions and expressed in terms of normalized response rates and fractional channel measures. To address the model dependence of the effective channel weights, we supplement the baseline calculation with a weight-sensitivity analysis in which the leading channel is penalized while competing channels are enhanced. Within the adopted literature-guided phenomenological parameterization, Si remains electron-dominated, GaAs remains phonon-dominated under moderate adverse perturbations, and NiO remains magnon-dominated. However, the unit-weight test shows that the GaAs classification is conditional on including material-guided channel weighting, emphasizing that the present results should be interpreted as normalized comparative trends rather than absolute detector-rate predictions. The analysis therefore supports a cautious material-specialization picture: semiconducting, polar, and magnetic targets can preferentially emphasize different low-energy excitation signatures, but the quantitative hierarchy depends on the adopted response functions, channel weights, thresholds, and interaction assumptions. The study provides a transparent baseline for organizing multi-target detection strategies and identifies the main limitations that must be addressed by future microscopic or ab initio calculations.