Second-Harmonic Generation by Reconfigurable Lattice Engineering in Centrosymmetric Magnetic CrSBr

Second-harmonic generation in centrosymmetric magnetic materials is typically restricted below the Néel temperature; above this threshold, symmetry breaking requires the application of external fields. Here, we report the first observation of robust second-harmonic generation at ambient temperature in a centrosymmetric magnetic material without the application of external stimuli. By integrating chromium sulfide bromide (with a Néel temperature of 136 K) with aligned silver nanowires, we simultaneously induce uniaxial strain and plasmonic near-field enhancement, driving a persistent structural transition from orthorhombic to monoclinic symmetry. This dual activation mechanism enables the coexistence of anisotropic strain-induced and magnetization-assisted second-harmonic generation, yielding a strong nonlinear optical response under ambient conditions. Furthermore, we demonstrate a functional magneto-optical device operating under ambient, establishing a broadly applicable framework for accessing nonlinear optical phenomena in centrosymmetric quantum materials at room temperature.