APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016;
Baltimore, Maryland
Session C19: Epitaxial Engineering of Magnetic Oxide Thin Films
2:30 PM–5:30 PM,
Monday, March 14, 2016
Room: 318
Sponsoring
Units:
GMAG DMP
Chair: Mark Huijben, University of Twente
Abstract ID: BAPS.2016.MAR.C19.1
Abstract: C19.00001 : Epitaxial Engineering of Domain Walls and Distortions in Ferrite Heterostructures.
2:30 PM–3:06 PM
Preview Abstract
Abstract
Author:
Julia Mundy
(UC Berkeley)
The defining feature of ferroics is the ability of an external
stimulus---electric field, magnetic field, or stress---to move domain walls.
These topological defects and their motion enables many useful attributes,
e.g., memories that can be reversibly written between stable states as well
as enhanced conductivity, permittivity, permeability, and piezoelectricity.
Although methods are known to drastically increase their density, the
placement of domain walls with atomic precision has until now evaded
control. Here we engineer the location of domain walls with monolayer
precision and exploit this ability to create a novel multiferroic in which
ferroelectricity enhances magnetism at all relevant length scales. Starting
with hexagonal LuFeO$_{\mathrm{3}}$, a geometric ferroelectric with the
greatest known planar rumpling, we introduce individual extra monolayers of
FeO during growth to construct formula-unit-thick syntactic layers of
ferrimagnetic LuFe$_{\mathrm{2}}$O$_{\mathrm{4}}$ within the
LuFeO$_{\mathrm{3}}$ matrix, i.e.,
(LuFeO$_{\mathrm{3}})_{m}$/(LuFe$_{\mathrm{2}}$O$_{\mathrm{4}})_{\mathrm{1}}$
superlattices. The severe rumpling imposed by the neighboring
LuFeO$_{\mathrm{3}}$ drives the ferrimagnetic
LuFe$_{\mathrm{2}}$O$_{\mathrm{4}}$ into a simultaneously ferroelectric
state and reduces the LuFe$_{\mathrm{2}}$O$_{\mathrm{4}}$ spin frustration.
This increases the magnetic transition temperature significantly---to 281 K
for the
(LuFeO$_{\mathrm{3}})_{\mathrm{9}}$/(LuFe$_{\mathrm{2}}$O$_{\mathrm{4}})_{\mathrm{1}}$
superlattice. Moreover, LuFeO$_{\mathrm{3}}$ can form charged ferroelectric
domain walls, which we align to the LuFe$_{\mathrm{2}}$O$_{\mathrm{4}}$
bilayers with monolayer precision. Charge transfers to these domain walls to
alleviate the otherwise electrostatically unstable polarization arrangement,
further boosting the magnetic moment. Our results demonstrate the utility of
combining ferroics at the atomic-layer level with attention to domain walls,
geometric frustration and polarization doping to create multiferroics by
design.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2016.MAR.C19.1