Potential effect of the deformation of strong-coupling polaron in perovskite materials

The electronic structure of perovskite nanomaterial systems can change when exposed to mechanical stress, a fact that has been extensively applied in the investigation of polaron properties. A deformation potential is formed when interactions among charge carriers and the lattice are mediated by stress. Hence, the deformation potential can be considered an important tool to explore acoustic polaron properties. In this research, we adopted a theoretical method by combining unitary transformation and second quantization, incorporating the deformation potential effect into the polaron effect. Finally, we derived the effective mass and ground-state energy of strongly coupled bound polarons in perovskite lattices. Through in-depth analysis and numerical calculations, we found that under the combined influence of sound velocity and deformation potential, the polaron coupling strength no longer remained constant; instead, it exhibited a variation with the perovskite lattice deformation potential. In addition, the ground-state energy, vibrational frequency, and effective mass of the polaron displayed anomalous behaviors. This research provides an important reference to further understand the physical characteristics of acoustic polarons formed by lattice distortions.