1,149 research outputs found
Low-Temperature Deposition of Pb(Zr,Ti)O3 Thin Films on Si Substrates Using Ba(Mg1/3Ta2/3)O3 as Buffer Layer
[[abstract]]Utilization of Ba(Mg1/3Ta2/3)O3 materials as buffer layers was found to achieve perovskite Pb(Zr,Ti)O3 (PZT) thin film growth on silicon at very low substrate temperature (∼350 °C) by in situ pulsed laser deposition (PLD). Formation of a continuous layer is of critical importance in order to use the Ba(Mg1/3Ta2/3)O3 materials as diffusion barriers for suppressing the PZT-to-Si interaction and, at the same time, as seeding layers for enhancing the crystallization kinetics of the PZT films. Perovskite and amorphous PZT thin films can be obtained by simply adjusting the ambient oxygen pressure or substrate temperature in the PLD process. The amorphous PZT films possess a markedly smaller optical refractive index than the perovskite ones (namorphous = 2.02 and nperovskite = 2.39), such that the perovskite/amorphous PZT films are a good combination for core/cladding materials for planar optical waveguides.[[fileno]]2020305010029[[department]]材料科學工程學
Mean Shift-Based Mobile Localization Method in Mixed LOS/NLOS Environments for Wireless Sensor Network
Mobile localization estimation is a significant research topic in the fields of wireless sensor network (WSN), which is of concern greatly in the past decades. Non-line-of-sight (NLOS) propagation seriously decreases the positioning accuracy if it is not considered when the mobile localization algorithm is designed. NLOS propagation has been a serious challenge. This paper presents a novel mobile localization method in order to overcome the effects of NLOS errors by utilizing the mean shift-based Kalman filter. The binary hypothesis is firstly carried out to detect the measurements which contain the NLOS errors. For NLOS propagation condition, mean shift algorithm is utilized to evaluate the means of the NLOS measurements and the data association method is proposed to mitigate the NLOS errors. Simulation results show that the proposed method can provide higher location accuracy in comparison with some traditional methods
Thickness dependence of the anomalous Hall effect in thin films of the topological semimetal CoMnGa
Topological magnetic semimetals promise large Berry curvature through the
distribution of the topological Weyl nodes or nodal lines and further novel
physics with exotic transport phenomena. We present a systematic study of the
structural and magnetotransport properties of CoMnGa films from thin (20
nm) to bulk like behavior (80 nm), in order to understand the underlying
mechanisms and the role on the topology. The magnetron sputtered CoMnGa
films are -ordered showing very good heteroepitaxy and a
strain-induced tetragonal distortion. The anomalous Hall conductivity was found
to be maximum at a value of 1138 S/cm, with a corresponding anomalous Hall
angle of 13 %, which is comparatively larger than topologically trivial metals.
There is a good agreement between the theoretical calculations and the Hall
conductivity observed for the 80 nm film, which suggest that the effect is
intrinsic. Thus, the CoMnGa compound manifests as a promising material
towards topologically-driven spintronic applications.Comment: 7 pages, 5 figures, 1 tabl
Structural study in Highly Compressed BiFeO3 Epitaxial Thin Films on YAlO3
We report a study on the thermodynamic stability and structure analysis of
the epitaxial BiFeO3 (BFO) thin films grown on YAlO3 (YAO) substrate. First we
observe a phase transition of MC-MA-T occurs in thin sample (<60 nm) with an
utter tetragonal-like phase (denoted as MII here) with a large c/a ratio
(~1.23). Specifically, MII phase transition process refers to the structural
evolution from a monoclinic MC structure at room temperature to a monoclinic MA
at higher temperature (150oC) and eventually to a presence of nearly tetragonal
structure above 275oC. This phase transition is further confirmed by the
piezoforce microscopy measurement, which shows the rotation of polarization
axis during the phase transition. A systematic study on structural evolution
with thickness to elucidate the impact of strain state is performed. We note
that the YAO substrate can serve as a felicitous base for growing T-like BFO
because this phase stably exists in very thick film. Thick BFO films grown on
YAO substrate exhibit a typical "morphotropic-phase-boundary"-like feature with
coexisting multiple phases (MII, MI, and R) and a periodic stripe-like
topography. A discrepancy of arrayed stripe morphology in different direction
on YAO substrate due to the anisotropic strain suggests a possibility to tune
the MPB-like region. Our study provides more insights to understand the strain
mediated phase co-existence in multiferroic BFO system.Comment: 18 pages, 6 figures, submitted to Journal of Applied Physic
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