Layered perovskites with giant spontaneous polarizations for nonvolatile memories

Abstract

A series of titanate-based layered perovskites having large values of the spontaneous polarization P-s were developed for their applcations to nonvolatile ferroelectric random access memories. Among these, the Nd-modified bismuth titanate [Bi4-xNdxTi3O12 (BNdT)] system exhibited the most remarkable ferroelectric properties. The c-axis oriented BNdT capacitor was characterized by a switchable remanent polarization 2P(r) of over 100 muC/cm(2) and imprinting and fatigue-free behavior. The active Ti site responsible for the giant P-s was identified with the help of Rietveld analysis, x-ray absorption near-edge structure study, and ab initio quantum computations.