Alleviating polarity-conflict at the heterointerfaces of KTaO${}_3$/GdScO${}_3$ polar complex-oxides

We have synthesized and investigated the heterointerfaces of KTaO${}_3$ (KTO) and GdScO${}_3$ (GSO), which are both polar complex-oxides along the pseudo-cubic [001] direction. Since their layers have the same, conflicting net charges at interfaces, i.e. KO(-1)/ScO${}_2$(-1) or TaO${}_2$(+1)/GdO(+1), forming the heterointerface of KTO/GSO should be forbidden due to strong Coulomb repulsion, the so-called $\mathit{\text{polarity}}\mathit{\text{conflict}}$. However, we have discovered that atomic reconstruction occurs at the heterointerfaces between KTO thin-films and GSO substrates, which effectively alleviates the polarity conflict without destroying the hetero-epitaxy. Our result demonstrates one of the important ways to create artificial heterostructures from polar complex-oxides.