Towards the limit of ferroelectric nanostructures: switchable sub-10 nm nanoisland arrays

Ultrahigh density arrays of ferroelectric PbTiO₃ (PTO) nanoislands with various feature sizes were epitaxially grown by utilizing block copolymer micelles. Piezoresponse and ferroelectric properties were clearly observed in the PTO nanoislands by band excitation piezoresponse force microscopy. In particular, PTO nanoislands were fully switchable even with a volume as small as 79 nm³. Accordingly, it is expected that the volume of the switchable ferroelectric nanoislands can be further decreased. The obtained results show that an areal density of over 10 Tb in⁻² for the ferroelectric memory devices would be possible.