Robust polarization switching in self-assembled BiFeO₃ nanoislands with quad-domain structures

Miniaturizing ferroic oxides is essential for studying the fundamental physics of low-dimensional topological defects such as flux-closure vortex as well as the applications of future nanoelectronic devices. Here, we successfully synthesized self-assembled BiFeO₃ nanoislands on LaAlO₃ (001) substrate by pulsed laser deposition. Center-type quad-domains are spontaneously stabilized in these nanostructures, and the polarization vectors of each quarter can be independently switched with robust retention properties over time and elevated temperature. As a result, the long-sought exotic domain structures such as anti-vertex can be created in these nanoislands by selectively switching polarization state of certain quarters. Resistive switching effect is also confirmed in quarters of the nanoisland, indicating the great potential as memory cells in high density ferroelectric random access memory.