24,480 research outputs found
More ferroelectrics discovered by switching spectroscopy piezoresponse force microscopy?
The local hysteresis loop obtained by switching spectroscopy piezoresponse
force microscopy (SS-PFM) is usually regarded as a typical signature of
ferroelectric switching. However, such hysteresis loops were also observed in a
broad variety of non-ferroelectric materials in the past several years, which
casts doubts on the viewpoint that the local hysteresis loops in SS-PFM
originate from ferroelectricity. Therefore, it is crucial to explore the
mechanism of local hysteresis loops obtained in SS-PFM testing. Here we
proposed that non-ferroelectric materials can also exhibit amplitude butterfly
loops and phase hysteresis loops in SS-PFM testing due to the Maxwell force as
long as the material can show macroscopic D-E hysteresis loops under cyclic
electric field loading, no matter what the inherent physical mechanism is. To
verify our viewpoint, both the macroscopic D-E and microscopic SS-PFM testing
are conducted on a soda-lime glass and a non-ferroelectric dielectric material
Ba0.4Sr0.6TiO3. Results show that both materials can exhibit D-E hysteresis
loops and SS-PFM phase hysteresis loops, which can well support our viewpoint.Comment: 12 pages,4 figure
Dynamic Behavior in Piezoresponse Force Microscopy
Frequency dependent dynamic behavior in Piezoresponse Force Microscopy (PFM)
implemented on a beam-deflection atomic force microscope (AFM) is analyzed
using a combination of modeling and experimental measurements. The PFM signal
comprises contributions from local electrostatic forces acting on the tip,
distributed forces acting on the cantilever, and three components of the
electromechanical response vector. These interactions result in the bending and
torsion of the cantilever, detected as vertical and lateral PFM signals. The
relative magnitudes of these contributions depend on geometric parameters of
the system, the stiffness and frictional forces of tip-surface junction, and
operation frequencies. The dynamic signal formation mechanism in PFM is
analyzed and conditions for optimal PFM imaging are formulated. The
experimental approach for probing cantilever dynamics using frequency-bias
spectroscopy and deconvolution of electromechanical and electrostatic contrast
is implemented.Comment: 65 pages, 15 figures, high quality version available upon reques
PFM Simulator
Pulse frequency modulation simulator for design and testing of telemetry equipment for satellite system
Quantitative analysis of ferroelectric domain imaging with piezoresponse force microscopy
The contrast mechanism for ferroelectric domain imaging via piezoresponse
force microscopy (PFM) is investigated. A novel analysis of PFM measurements is
presented which takes into account the background caused by the experimental
setup. This allows, for the first time, a quantitative, frequency independent
analysis of the domain contrast which is in good agreement with the expected
values for the piezoelectric deformation of the sample and satisfies the
generally required features of PFM imaging
Effect of the Intrinsic Width on the Piezoelectric Force Microscopy of a Single Ferroelectric Domain Wall
Intrinsic domain wall width is a fundamental parameter that reflects bulk
ferroelectric properties and governs the performance of ferroelectric memory
devices. We present closed-form analytical expressions for vertical and lateral
piezoelectric force microscopy (PFM) profiles for the conical and disc models
of the tip, beyond point charge and sphere approximations. The analysis takes
into account the finite intrinsic width of the domain wall, and dielectric
anisotropy of the material. These analytical expressions provide insight into
the mechanisms of PFM image formation and can be used for quantitative analysis
of the PFM domain wall profiles. PFM profile of a realistic domain wall is
shown to be the convolution of its intrinsic profile and resolution function of
PFM.Comment: 25 pages, 5 figures, 3 tables, 3 Appendices, To be submitted to J.
Appl. Phy
Depth resolution of Piezoresponse force microscopy
Given that a ferroelectric domain is generally a three dimensional entity, the determination of its area as well as its depth is mandatory for full characterization. Piezoresponse force microscopy (PFM) is known for its ability to map the lateral dimensions of ferroelectric domains with high accuracy. However, no depth profile information has been readily available so far. Here, we have used ferroelectric domains of known depth profile to determine the dependence of the PFM response on the depth of the domain, and thus effectively the depth resolution of PFM detection
Brownian motion in a non-homogeneous force field and photonic force microscope
The Photonic Force Microscope (PFM) is an opto-mechanical technique based on
an optical trap that can be assumed to probe forces in microscopic systems.
This technique has been used to measure forces in the range of pico- and
femto-Newton, assessing the mechanical properties of biomolecules as well as of
other microscopic systems. For a correct use of the PFM, the force field to
measure has to be invariable (homogeneous) on the scale of the Brownian motion
of the trapped probe. This condition implicates that the force field must be
conservative, excluding the possibility of a rotational component. However,
there are cases where these assumptions are not fulfilled Here, we show how to
improve the PFM technique in order to be able to deal with these cases. We
introduce the theory of this enhanced PFM and we propose a concrete analysis
workflow to reconstruct the force field from the experimental time-series of
the probe position. Furthermore, we experimentally verify some particularly
important cases, namely the case of a conservative or rotational force-field
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