Exploring Structural Anisotropy and Anharmonicity in 2D Nanomaterials

Crystallographic anisotropy, be it inherent or externally induced, profoundly impacts the materials’ physical properties, contributing to their ground-state morphology and magnetic arrangement and fostering distinctive optical behavior. Two-dimensional (2D) materials provide a relatively non-complex platform to study these anisotropy-driven properties. This review explores the intricate relationship between structural anisotropy and the resulting physical phenomena in 2D materials, primarily focusing on 2D hybrid perovskites (2D HPs) and transition metal phosphorous trichalcogenides. Case studies of 2D PEA₂PbI₄ HPs and FePS₃ are provided, explaining how intrinsic structural anisotropy originates and manifests as ground state polymorphism in 2D HPs and zigzag antiferromagnetic arrangement in FePS₃. The case of alloyed MnPS₃ is examined, where extrinsically induced anisotropy induces magnetic disorder, impacting its magnetic phase stability and overall optical behavior. This account, thus, underscores the origin and significance of intrinsic and extrinsic anisotropy in manipulating materials’ properties.