Journal Article ferroelectricity BaTiO3 CO2 laser heating LuFeO3 SrRuO3 angle-resolved photoemission spectroscopy correlated electron systems density functional theory dynamical mean-field theory electronic reconstruction epitaxial oxide heterostructures epitaxial ultrathin films ferroelectric critical thickness ferromagnetism hexagonal ferrites high‐temperature epitaxy interface control interface engineering magnetoelectric coupling metal-insulator transition morphotropic phase mixtures multiferroics oxygen diffusion quantum tunneling ruthenates surface termination engineering terrace edges titanium oxide ultrathin oxide films