Programming
the self-assembly
of alloy nanowires:
a combinatorial approach
Ferromagnetic nanowires are interesting
objects for fundamental studies
in nanomagnetism. Finding ways
to obtain wires with reduced diameters
and controlled composition and structure
is thus an important task. This work reports
on a new approach, relying on self-assembly,
for growing epitaxial alloy nanowires
assemblies in a matrix. It allows one
to obtain epitaxial wires, with 4 nm
diameters, and controlled composition
and magnetic anisotropy.
Heteroepitaxy of horizontal structures
is a well-established way of obtaining
coherent stacking of different materials
and thus developing systems with new
properties of interest in many areas
of physics, including optoelectronics,
magnetism and spin electronics.
In recent years new types of vertical
epitaxial heterostructures have emerged,
where a material grows epitaxially
in the form of nano-pillars or nanowires
in the matrix of another material. This
geometry might lead to progress in the
field of multi-functional nano-composites
or even to strain-engineering by controlling
deformations along the wire axis.
The method used in this study is based
on a combinatorial approach to pulsed
laser ablation, illustrated in Figure
➊
.
Controlled amounts of Co, Ni and cerium
oxide are deposited sequentially, in a
sub-monolayer regime, on a SrTiO
3
(001)
substrate.
This results in the self-assembly
of Co
x
Ni
1-x
alloy nanowires embedded
in a monocrystalline CeO
2
/SrTiO
3
(001)
matrix. The diameter of the wires is very
small (4 nm) and their density can exceed
1 Tb/inch
2
.
Introduction
A new technique for obtaining alloy nanowires
PHYSICS AND CHEMISTRY OF CONDENSED MATTER, EARTH SCIENCES
➊
Diagram explaining the combinatorial method
used for the epitaxial growth of cobalt-nickel alloy
nanowires in CeO
2
/SrTiO
3
(001). By adjusting
the sequence of laser shots on the target to deposit
the cobalt, nickel and matrix in controlled quantities
in sub-monolayers, it is possible to obtain self-
assembled cobalt-nickel alloy vertical nanowires
embedded in the matrix.
96
SOLEIL
HIGHLIGHTS
2013
