Interplay of field-induced molecular dipole alignment and compensating surface polarization in low-temperature P-V hysteresis of MAPbBr₃(001)

We demonstrate the presence of a hysteresis in tunneling spectra acquired at 4.3 K on cleaved MA-Br terminated (001) surfaces of MAPbBr(3) single crystals. Simulations of the tunneling spectra reveal an underlying polarization-voltage (P-V) hysteresis, which is caused by an interplay of subsurface field-induced rotation and alignment of the MA molecules, stabilized by dipole-dipole interactions, and an ion-lattice relaxation. The resulting subsurface polarization is counteracted by a compensating surface polarization, detectable by surface-sensitive tunneling spectroscopy.