Alessio Morelli

Domain switching in multiferroic bismuth ferrite nanoislands.
1
A.Morelli*1, R. McQuaid1, and J.M. Gregg1
Centre of nanostructured media, School of Physics and Mathematics,
Queen’s University Belfast,
University Road, Belfast, United Kingdom, BT7 1NN
*e-mail: [email protected]
Electric field driven magnetization switching could lead to reductions in power consumption and
overheating in current nanoelectronic devices. In this regard, multiferroic magnetoelectric materials are the
focus of attention, and in particular room temperature ferroelectric antiferromagnetic bismuth ferrite (BFO)
is widely studied due to its unique properties1. It has been shown that in ferromagnetic/(001)pBFO
mesostructures electric field driven magnetization rotation can be achieved via an exchange bias mediated
interfacial magnetoelectric effect2,3. In order to attain unequivocal control of magnetization in
perpendicular heterostructures, deterministic ferroelastic/ferroelectric polarization switching in (001)pBFO
firstly needs to be achieved: to this effect investigations are currently ongoing3,4. However, switching
procedures in thin films or mesostructures are influenced by the boundary conditions imposed on the area
under investigation by the ferroelectric state of the surrounding matrix material5. Therefore, in order to
fully understand and control such mechanism in (001)pBFO, it would be desirable to study the phenomenon
in free standing nanoislands.
Here we apply an ion beam milling fabrication procedure6 to obtain BFO nanoislands out of a thin film.
The switching properties are investigated by piezoresponse force microscopy, in relation to size and
electrode configuration. Preliminary investigations show that switching is achievable in 250nm and 150nm
diameter nanoislands, with good retention properties. However, in order to understand and tune the
ferroelectric/ferroelastic switching procedure, polarization control of the structures as a whole is desired,
which would require the presence of a top electrode.
Such investigations would yield a deeper understanding of the switching mechanism in BFO, and would
eventually lead to utilization of composite multiferroics for nanoelectronic devices.
1. Epitaxial BiFeO3 multiferroic thin film heterostructures, Wang J et al., Science 299, p.1719 (2003).
2. Electric-field control of local ferromagnetism using a magnetoelectric multiferroic, Chu Y H et al., Nat.
Mat 7, p.478 (2008).
3. Deterministic switching of ferromagnetism at room temperature using an electric field, Heron J T, et al.,
Nature 516, p.370 (2014).
4. Deterministic control of ferroelastic switching in m ultiferroic materials, Balke N, et al., Nat. Nan. 4,
p.868 (2009).
5. Ferroelastic switching for nanoscale non-volatile magnetoelectric devices, Baek S H et al., Nat. Mater. 9,
p.309 (2010).
6. Mask assisted fabrication of nanoislands of BiFeO3 by ion beam milling, Morelli A et al., J. Appl. Phys.
113, p.154101 (2013).
CV Alesssio Morelli
Dr. A. Morelli obtained his PhD from University of Groningen (NL) in 2009 where
his research focused on scanning probe microscopy of ferroelectric thin films. He
was a postdoctoral research associate in Max Planck Institute, Halle (DE) where
his work revolved on multiferroic nanostructures, and in the Institute of Physics,
Prague (CZ) on nanoscale characterization of ferroelectric materials. He is
currently a Marie Curie fellow at Queen’s University Belfast (UK) within the
Centre for Nanostructured Media, with a research project aiming at the
investigation of electric field driven magnetization switching in multiferroic
nanoislands.