Effective Pyroelectric Coefficient and Polarization Offset of Compositionally Step-like Graded Ferroelectric Structures

In this paper, the effective pyroelectric coefficientand polarization offset ofthe compositionally step-like graded multilayer ferroelectric structureshave been studied by use of the first-principles approach.It is exhibited that the dielectric gradient has a nontrivial influenceon the effective pyroelectric coefficient, but has a little influenceon the polarization offset; and the polarization gradientplays an important role in the abnormal hysteresis loop phenomenonof the compositionally step-like graded ferroelectric structures.Moreover, the origin of the polarization offset is explored,which can be attributed to the polarization gradientin the compositionally step-like graded structure.