2D Polar Supercrystal Phase in Lacunar Spinels

Non-centrosymmetric lacunar spinels like GaMo₄S₈ host an exotic, Jahn-Teller effect driven polar state lacking antiphase ferroelectric domains at low temperature. Our preliminary cryogenic transmission electron microscopy data suggest that these domains form a 2D polar supercrystal state in thin GaMo₄S₈ lamellae. Here, we propose an in-situ scanning X-ray diffraction microscopy (SXDM) study of GaMo₄S₈ lamellae as a function of temperature to investigate the emergence of periodic domain patterns. Using ID01 at ESRF, we aim to spatially resolve the local lattice distortions and domain tilts, providing direct evidence of this new supercrystal structure emerging in polar non-ferroelectric materials.