10,074 research outputs found
Strain analysis of multiferroic BiFeO3-CoFe2O4 nanostructures by Raman scattering
We report a Raman scattering investigation of columnar BiFeO3-CoFe2O4
(BFO-CFO) epitaxial thin film nanostructures, where BFO pillars are embedded in
a CFO matrix. The feasibility of a strain analysis is illustrated through an
investigation of two nanostructures with different BFO-CFO ratios. We show that
the CFO matrix presents the same strain state in both nanostructures, while the
strain state of the BFO pillars depends on the BFO/CFO ratio with an increasing
tensile strain along the out-of-plane direction with decreasing BFO content.
Our results demonstrate that Raman scattering allows monitoring strain states
in complex 3D multiferroic pillar/matrix composites.Comment: revised version submitted to Appl. Phys. Let
Induced magnetization in LaSrMnO/BiFeO superlattices
Using polarized neutron reflectometry (PNR), we observe an induced
magnetization of 75 25 kA/m at 10 K in a LaSrMnO
(LSMO)/BiFeO superlattice extending from the interface through several
atomic layers of the BiFeO (BFO). The induced magnetization in BFO is
explained by density functional theory, where the size of bandgap of BFO plays
an important role. Considering a classical exchange field between the LSMO and
BFO layers, we further show that magnetization is expected to extend throughout
the BFO, which provides a theoretical explanation for the results of the
neutron scattering experiment.Comment: 5 pages, 4 figures, with Supplemental Materials. To appear in
Physical Review Letter
Spin transfer in ultrathin BiFeO3 film under external electric field
First-principals calculations show that up-spin and down-spin carriers are
accumulating adjacent to opposite surfaces of BiFeO3(BFO) film with applying
external bias. The spin carriers are equal in magnitude and opposite in
direction, and down-spin carriers move to the direction opposing the external
electric field while up-spin ones along the field direction. This novel spin
transfer properties make BFO film an intriguing candidate for application in
spin capacitor and BFO-based multiferroic field-effect device
Interfacial effects on the polarization of films
By considering an interfacial layer between the electrode and the
() layer, the polarization and the hysteresis behavior of
film are simulated. It is found that the non-ferroelectric interface will
increase the coercive field, and remarkably suppress the polarization of the
ultrathin film under low applied fields. Due to the competition between the
interfacial effect and the internal compressive stress, the maximum
polarization on the P-E loop of a film can be independent on the film
thickness under an adequate applied field.Comment: 3 pages, 2 figure
Polaronic transport induced by competing interfacial magnetic order in a LaCaMnO/BiFeO heterostructure
Using ultrafast optical spectroscopy, we show that polaronic behavior
associated with interfacial antiferromagnetic order is likely the origin of
tunable magnetotransport upon switching the ferroelectric polarity in a
LaCaMnO/BiFeO (LCMO/BFO) heterostructure. This is
revealed through the difference in dynamic spectral weight transfer between
LCMO and LCMO/BFO at low temperatures, which indicates that transport in
LCMO/BFO is polaronic in nature. This polaronic feature in LCMO/BFO decreases
in relatively high magnetic fields due to the increased spin alignment, while
no discernible change is found in the LCMO film at low temperatures. These
results thus shed new light on the intrinsic mechanisms governing
magnetoelectric coupling in this heterostructure, potentially offering a new
route to enhancing multiferroic functionality
A First-Order Logic Formalization of the Industrial Ontology Foundry Signature Using Basic Formal Ontology
Basic Formal Ontology (BFO) is a top-level ontology used in hundreds of active projects in scientific and other domains. BFO has been selected to serve as top-level ontology in the Industrial Ontologies Foundry (IOF), an initiative to create a suite of ontologies to support digital manufacturing on the part of representatives from a number of branches of the advanced manufacturing industries. We here present a first draft set of axioms and definitions of an IOF upper ontology descending from BFO. The axiomatization is designed to capture the meanings of terms commonly used in manufacturing and is designed to serve as starting point for the construction of the IOF ontology suite
Function, Role, and Disposition in Basic Formal Ontology
Numerous research groups are now utilizing Basic Formal Ontology (BFO) as an upper-level framework to assist in the organization and integration of biomedical information. This paper provides elucidation of the three BFO categories of function, role, and disposition, and considers two proposed sub-categories of artifactual function and bio-logical function. The motivation is to help advance the coherent treatment of functions, roles, and dispositions, to help provide the potential for more detailed classification, and to shed light on BFO’s general structure and use
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