Fabrication of 109° Periodic Domain Walls with a Bottom Electrode in BiFeO3 Thin Films

Summary

109° periodic domain walls can successfully be fabricated by introducing a dielectric La-BiFeO₃ layer between a bottom electrode and a ferroelectric BiFeO₃ layer, enabling the study of the switching behavior of a 109° domain structure and the investigation of the electric field control of exchange bias in a ferromagnet/BiFeO₃ system.

Abstract

A variety of exciting phenomena have been discovered using 109° domain walls in BiFeO₃ thin films, such as domain wall conductivity, photovoltaic effects, and magnetoelectric coupling effects. The control of these physical properties with an electric field plays a key role in the development of nanoelectric devices. Therefore, it is critical to fabricate 109° periodic domain walls with a bottom electrode. However, the introduction of a bottom electrode favors the formation of a 71° domain structure due to the electrostatic boundary conditions. In this study, pulsed laser deposition (PLD) is used to produce multilayer epitaxial thin films. A 25% La doping BiFeO₃ layer is inserted as the dielectric spacer between the bottom electrode SrRuO₃ layer and the pure BiFeO₃ layer, enabling the fabrication of 109° periodic domain walls engineered by an interface effect-depolarization field. Moreover, the fabrication of the 109° domain structure with a bottom electrode enables the study of its switching behavior. This protocol provides a novel route to produce 109° periodic domain walls and opens a new pathway to explore fascinating phenomena, such as the room-temperature electric field control of exchange bias in a ferromagnet/BiFeO₃ system and room-temperature multiferroic vortices in BiFeO₃.

Introduction

Domain wall functionalities in BiFeO₃ thin films, such as domain wall conductivity¹, photovoltaic effects², magnetism³, and magnetoelectric coupling⁴, have inspired many studies on the fabrication and manipulation of the domain structures^5,6,7. Periodically ordered 71°, 109°, and 180° stripe domains have been obtained by tuning the film thickness effects, misfit strain effects, and electrostatic boundary conditions^8,

Protocol

1. Substrate Preparation

1. Clean a 5 mm × 5 mm × 0.5 mm single-crystal DyScO₃ (110) substrate with acetone in an ultrasonic cleaner for 5 min.
2. Rinse the substrate with acetone for 5 s and transfer it to isopropyl alcohol. Clean it for 5 min in the ultrasonic cleaner.
3. Rinse the substrate with isopropyl alcohol for 5 s and dry it using N₂ flow.
4. Mount the substrate on a heater with silver paint and then put the heater on a hot plate to dry the silver pa.......

Discussion

PLD is a powerful technique to fabricate complex oxide epitaxial thin films¹⁹. Using this technique, many investigations have been carried out on BiFeO₃ thin films^13,20,21,22. As one of the most striking aspects, domain walls are widely studied due to a wealth of fascinating phenomena^1,2,

Materials

Name	Company	Catalog Number	Comments
Pulsed Laser	Coherent	Complex Pro 205 F
Power Meter	Coherent	FieldMaxII
Target	Home Made	Made on request
Piezoresponse Force Microscopy	Oxford Insturments	MFP-3D Infinity Asylum Research AFM
Isopropyl Alcohol	Fisher Chemical	A415-4
Actone	Fisher Chemical	A949-4