Formation of long-range in-plane polarization order in Bi2WO6 thin films

Symmetry breaking gives rise to intriguing physical phenomena, offering emergent concepts for next-generation memory devices. Ferroelectric oxide thin films, as inherently non-centrosymmetric systems, exhibit diverse optical, electrical, and magnetic properties. In this study, we grow bismuth tungsten oxide (Bi2WO6) thin films on various oxide substrates. Piezoresponse force microscopy reveals that Bi2WO6 grown on rhombohedral NdAlO3 (001) substrates adopts a quasi-monodomain configuration, which we attribute to twin-induced local vicinality of the substrate. Raman spectroscopy further uncovers a direct correlation between in-plane domain orientation and phonon modes, with the 305 cm−1 mode specifically linked to the domain direction. These findings establish a pathway for optical detection and dynamic investigation of in-plane domains in Bi2WO6 thin films, highlighting their potential for functional device applications.