Interlocked chiral/polar domain walls and large optical rotation in Ni₃TeO₆

Chirality, i.e., handedness, pervades much of modern science from elementary particles, DNA-based biology to molecular chemistry; however, most of the chirality-relevant materials have been based on complex molecules. Here, we report inorganic single-crystalline Ni₃TeO₆, forming in a corundum-related R3 structure with both chirality and polarity. These chiral Ni₃TeO₆ single crystals exhibit a large optical specific rotation (α) - 1355°dm^-1 cm³ g^-1. We demonstrate, for the first time, that in Ni₃TeO₆, chiral and polar domains form an intriguing domain pattern, resembling a radiation warning sign, which stems from interlocked chiral and polar domain walls through lowering of the wall energy.