“…Perovskite lead zirconium titanate [Pb(Zr,Ti)O 3 ; PZT] ( 11 ) having large polarization, fast polarization switching, high Curie temperature, low coercive field, and a high piezoelectric coefficient, is probably the most explored system for these applications. The flexible version of polycrystalline PZT–based NVM has been demonstrated on Si ( 12 , 13 ), Pt foil ( 14 ), Cu foil ( 15 ), and Ni superalloy ribbons ( 16 ) or built on Si and then transferred on to flexible polymer substrates ( 17 , 18 ). It has long been postulated that single-crystalline functional oxides could resolve the critical issue of memory retention time in current technologies.…”