Ferroelectric and Magnetic Domains in LuFe2O4 Observed by Scanning Probe Microscopy

TL;DR

This study uses scanning probe microscopy techniques to image and analyze ferroelectric and magnetic domains in LuFe2O4, revealing their electronic origin, irregular patterns, and intrinsic formation mechanisms.

Contribution

It provides the first simultaneous imaging of ferroelectric and magnetic domains in LuFe2O4, demonstrating their intrinsic irregular patterns and differing length scales.

Findings

Ferroelectricity in LuFe2O4 is of electronic origin.

Ferroelectric domains are approximately 100 nm, magnetic domains up to 1 μm.

Domain patterns are irregular and intrinsically formed.

Abstract

LuFe2O4 is a multiferroic system which exhibits ferroelectricity, charge order, and ferrimagnetic order simultaneously below ~230 K. The ferroelectric domains of LuFe2O4 are imaged with both piezoresponse force microscopy (PFM) and electrostatic force microscopy (EFM), while the magnetic domains are characterized by magnetic force microscopy (MFM). Comparison of PFM and EFM results lead to a conclusion that the ferroelectricity is of electronic origin as opposed to the usual displacive one. Simultaneous characterization of ferroelectric and magnetic domains by EFM and MFM, respectively, on the same surface of LuFe2O4 reveals that both domains have irregular patterns of similar shape, but the length scales are quite different. The domain size is approximately 100 nm for the ferroelectric domains while the magnetic domain size is much larger and gets as large as 1{\mu}m. We also demonstrate that the origin of the formation of irregular domains in LuFe2O4 is not extrinsic but intrinsic.