Abstracts Book - IMRC 2018

• SA6-P038
DESIGN OF GALFENOL/PERMALLOY NANOLAMINATES FOR
INCORPORATION INTO A STRAIN-MEDIATED NANOSCALE
ANTENNA
Kevin Fitzell 1 , Colin Rementer 1 , Michelle Jamer 2 , Julie Borchers 2 , Brian Kirby 2 , Jane Chang 1
1 University of California, Los Angeles, Chemical Engineering, United States. 2 National Institute
of Standards and Technology, NIST Center for Neutron Research, United States.
The ability to reduce the size of antennae would enable a revolution in wearable
and implantable electronic devices. Strain-mediated nanoscale antennae based
on the magnetoelectric effect, composed of individual ferromagnetic and
piezoelectric phases, could reduce antenna size by up to five orders of
magnitude through the efficient coupling of magnetization and electric
polarization via strain. However, this strategy requires a magnetic material with
strong magnetoelastic coupling as well as low-loss magnetization dynamics in
the GHz range, a combination that is largely nonexistent in single-phase
materials.
Galfenol (FeGa) is a promising ferromagnetic material due to its large
magnetostriction (greater than 200 ppm), large piezomagnetic coefficient (3
ppm/Oe), and high stiffness (70 GPa), but it is very lossy in the GHz regime.
Permalloy (NiFe) is a soft magnetic material that has very low loss in the GHz
regime, with an FMR linewidth less than 20 Oe but almost no magnetostriction.
In this work, multilayer laminates containing alternating layers of FeGa and NiFe
were fabricated via DC magnetron sputtering and optimized for use at high
frequency through tuning the thickness and number of individual layers.
Optimized magnetic multilayers were found to combine the complementary
properties of FeGa and NiFe, exhibiting a small coercive field (less than 20 Oe),
narrow FMR linewidth (less than 40 Oe), high permeability (over 400), and strong
magnetostriction (more than 70 ppm) (Rementer et al., 2017). The magnetization
of each layer was also shown to rotate coherently in an applied magnetic field
via polarized neutron reflectometry.
Subsequent integration of these multilayer composites into microscale antenna
devices demonstrated the ability to produce a low-speed acoustic wave
electromagnetic radiation, showing great promise for FeGa/NiFe multilayers in
next-generation multiferroic antennae.