Magnetoelectric\nCoupling in Well-Ordered Epitaxial BiFeO₃/CoFe₂O₄/SrRuO₃ Heterostructured Nanodot Array

Abstract

Multiferroic\nmagnetoelectric (ME) composites exhibit sizable ME coupling at room\ntemperature, promising applications in a wide range of novel devices.\nFor high density integrated devices, it is indispensable to achieve\na well-ordered nanostructured array with reasonable ME coupling. For\nthis purpose, we explored the well-ordered array of isolated epitaxial\nBiFeO₃/CoFe₂O₄/SrRuO₃ heterostructured\nnanodots fabricated by nanoporous anodic alumina (AAO) template method.\nThe arrayed heterostructured nanodots demonstrate well-established\nepitaxial structures and coexistence of piezoelectric and ferromagnetic\nproperties, as revealed by transmission electron microscopy (TEM)\nand peizoeresponse/magnetic force microscopy (PFM/MFM). It was found\nthat the heterostructured nanodots yield apparent ME coupling, likely\ndue to the effective transfer of interface couplings along with the\nsubstantial release of substrate clamping. A noticeable change in\npiezoelectric response of the nanodots can be triggered by magnetic\nfield, indicating a substantial enhancement of ME coupling. Moreover,\nan electric field induced magnetization switching in these nanodots\ncan be observed, showing a large reverse ME effect. These results\noffer good opportunities of the nanodots for applications in high-density\nME devices, <i>e.g.</i>, high density recording (>100\nGbit/in.²) or logic devices.