Nonlinear optical (NLO) switch materials that turn on/off second‐harmonic generation (SHG) at a phase transition temperature (
Tc) are promising for applications in the fields of photoswitching and optical computing. However, precise control of
Tc remains challenging, mainly because a linearly tunable
Tc has not been reported to date. Herein, we report a unique selenate, tetragonal
P...