Switching Crystallographic Chirality in Ba(TiO)Cu₄(PO₄)₄ by Laser Irradiation

Switching crystallographic chirality is nontrivial because there is no simple conjugate field to chirality. Here we demonstrate chirality switching in an inorganic crystalline material by manipulating the boundaries of chiral domains with laser irradiation. Our study material is Ba(TiO)Cu₄(PO₄)₄, exhibiting a chiral structure at room temperature and a chiral-achiral phase transition at 710 °C. By irradiation of a laser beam with a wavelength at which Ba(TiO)Cu₄(PO₄)₄ exhibits strong optical absorption, local heating is induced. This leads to reconstructions of chiral domain boundaries, revealed by optical rotation measurements. In the reconstruction process, energetically unstable domain boundaries tend to be minimized, affecting resultant domain patterns. On the basis of this feature, we successfully manipulate chiral domain patterns by scanning the laser beam on the sample surface. Our findings provide a unique approach to controlling chirality in inorganic crystalline materials.