Early ferroelectric materials discovered more than 100 years ago like Rochelt salt were too unstable for widespread applications. Perovskite ferroelectrics like BaTiO3 (BTO) and later PbZrxTi1-x O3 (PZT) opened the path for widespread applications. Fist memory devices based on cross-point arrays involving BaTiO3 were proposed in the early 1950s [1]. However, it was not until semiconductor technology became mature that the first integrated capacitor-based memories involving PZT ferroelectrics became available in 1993 [2]. Ferroelectric memories remained a niche market due to the complexity of integrating oxide perovskites into CMOS and the related slow scaling. In 2011 Boescke et al. [3] published the observation of ferro electricity in hafnium oxide. This new material system has strongly increased the possibility to integrate ferroelectric functionalities into CMOS processes in the following years. Fig. 1 illustrates this development by showing the publication activity on the topic of 'ferroelectric memory'.