109 research outputs found
Site-Specific Plan-view (S)TEM Sample Preparation from Thin Films using a Dual-Beam FIB-SEM
Plan-view transmission electron microscopy (TEM) samples are key to
understand the atomic structure and associated properties of materials along
their growth orientation, especially for thin films that are stain-engineered
onto different substrates for property tuning. In this work, we present a
method to prepare high-quality plan-view samples for analytical STEM study from
thin-films using a dual-beam focused ion beam scanning electron microscope
(FIB-SEM) system. The samples were prepared from thin films of perovskite
oxides and metal oxides ranging from 20-80 nm thicknesses, grown on different
substrates using molecular beam epitaxy. A site-specific sample preparation
from the area of interest is described, which includes sample attachment and
thinning techniques to minimize damage to the final TEM samples. While
optimized for the thin film-like geometry, this method can be extended to other
site-specific plan-view samples from bulk materials. Aberration-corrected
scanning (S)TEM was used to access the quality of the thin film in each sample.
This enabled direct visualization of line defects in perovskite BaSnO3 and Ir
particle formation and texturing in IrO2 films
Efficient Spin-Orbit Torques in an Antiferromagnetic Insulator with Tilted Easy Plane
Electrical manipulation of spin textures inside antiferromagnets represents a
new opportunity for developing spintronics with superior speed and high device
density. Injecting spin currents into antiferromagnets and realizing efficient
spin-orbit-torque-induced switching is however still challenging due to the
complicated interactions from different sublattices. Meanwhile, because of the
diminishing magnetic susceptibility, the nature and the magnitude of
current-induced magnetic dynamics remain poorly characterized in
antiferromagnets, whereas spurious effects further complicate experimental
interpretations. In this work, by growing a thin film antiferromagnetic
insulator, {\alpha}-Fe2O3, along its non-basal plane orientation, we realize a
configuration where an injected spin current can robustly rotate the N\'eel
vector within the tilted easy plane, with an efficiency comparable to that of
classical ferromagnets. The spin-orbit torque effect stands out among other
competing mechanisms and leads to clear switching dynamics. Thanks to this new
mechanism, in contrast to the usually employed orthogonal switching geometry,
we achieve bipolar antiferromagnetic switching by applying positive and
negative currents along the same channel, a geometry that is more practical for
device applications. By enabling efficient spin-orbit torque control on the
antiferromagnetic ordering, the tilted easy plane geometry introduces a new
platform for quantitatively understanding switching and oscillation dynamics in
antiferromagnets.Comment: 21 pages, 5 figure
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