Observation of the Three-Dimensional Polarization Vector in Films of Organic Molecular Ferroelectrics Using Terahertz Radiation Emission

AbstractA significant body of work on simulating the remote appearance of Earth-like exoplanets has been done over the last decade. The research is driven by the prospect of characterizing habitable planets beyond the Solar System in the near future. In this work, I present a method to produce the disk-integrated signature of planets that are described in their three-dimensional complexity, i.e. with both horizontal and vertical variations in the optical properties of their envelopes. The approach is based on Pre-conditioned Backward Monte Carlo integration of the vector Radiative Transport Equation and yields the full Stokes vector for outgoing reflected radiation. The method is demonstrated through selected examples inspired by published work at wavelengths from the visible to the near infrared and terrestrial prescriptions of both cloud and surface albedo maps. I explore the performance of the method in terms of computational time and accuracy. A clear strength of this approach is that its computational cost does not appear to be significantly affected by non-uniformities in the planet optical properties. Earth's simulated appearance is strongly dependent on wavelength; both brightness and polarization undergo diurnal variations arising from changes in the planet cover, but polarization yields a better insight into variations with phase angle. There is partial cancellation of the polarized signal from the northern and southern hemispheres so that the outgoing polarization vector lies preferentially either in the plane parallel or perpendicular to the planet scattering plane, also for non-uniform cloud and albedo properties and various levels of absorption within the atmosphere. The evaluation of circular polarization is challenging; a number of one-photon experiments of 109 or more is needed to resolve hemispherically integrated degrees of circular polarization of a few times 10−5. Last, I introduce brightness curves of Earth obtained with one of the Messenger cameras at three wavelengths (0.48, 0.56 and 0.63 μm) during a flyby in 2005. The light curves show distinct structure associated with the varying aspect of the Earth's visible disk (phases of 98–107°) as the planet undergoes a full 24 h rotation; the structure is reasonably well reproduced with model simulations.

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Models of inhomogeneous polarization of ferroelectrics and their practical application

Journal of Advanced Dielectrics ◽

10.1142/s2010135x20600152 ◽

2020 ◽

Vol 10 (01n02) ◽

pp. 2060015

Author(s):

Alexander Skaliukh

Keyword(s):

Experimental Data ◽

Numerical Experiments ◽

Constitutive Relations ◽

Three Dimensional ◽

Polarization Vector ◽

Energy Costs ◽

Polarization Process ◽

Practical Application ◽

Real Polarization ◽

Good Agreement

A three-dimensional mathematical model is proposed that describes the ferroelectric response of polycrystalline ferroelectrics to an electric field in the absence of mechanical stresses. It is based on the separation of the switching process into two related parts: the rotation of the spontaneous polarization vectors and the destruction of the domain wall fixing mechanisms. For each of the parts, the energy costs are calculated, which are the components of the energy balance in the real polarization process. The constitutive relations for the induced and residual components of the polarization vector of the representative volume are obtained. A number of numerical experiments were performed, which showed good agreement with the experimental data.

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Terahertz radiation emission from plasma beat-wave interactions with a relativistic electron beam

Optics Communications ◽

10.1016/j.optcom.2017.05.043 ◽

2017 ◽

Vol 401 ◽

pp. 71-74 ◽

Cited By ~ 4

Author(s):

D.N. Gupta ◽

V.V. Kulagin ◽

H. Suk

Keyword(s):

Electron Beam ◽

Relativistic Electron ◽

Terahertz Radiation ◽

Relativistic Electron Beam ◽

Wave Interactions ◽

Radiation Emission

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Nanoscale Phenomena in Synthetic Functional Oxide Heterostructures

Microscopy and Microanalysis ◽

10.1017/s1431927602020287 ◽

2002 ◽

Vol 8 (4) ◽

pp. 333-349 ◽

Cited By ~ 7

Author(s):

V. Nagarajan ◽

C.S. Ganpule ◽

A. Stanishevsky ◽

B.T. Liu ◽

R. Ramesh

Keyword(s):

Thin Films ◽

Lead Zirconate Titanate ◽

Domain Walls ◽

Three Dimensional ◽

Polarization Vector ◽

Scanning Force Microscopy ◽

Lead Zirconate ◽

Quantitative Information ◽

Ferroelectric Thin Films ◽

Relaxation Dynamics

This paper reviews nanoscale phenomena such as polarization relaxation dynamics and piezoelectric characterization in model ferroelectric thin films and nanostructures using voltage-modulated scanning force microscopy. Using this technique we show the three-dimensional reconstruction of the polarization vector in lead zirconate titanate (PZT) thin films. Second, the time-dependent relaxation of remanent polarization in epitaxial PZT ferroelectric thin films, containing a uniform two-dimensional grid of 90° domains (c-axis in the plane of the film), has been investigated extensively. The 90° domain walls preferentially nucleate the 180° reverse domains during relaxation. Relaxation occurs through the nucleation and growth of reverse 180° domains, which subsequently coalesce and consume the entire region as a function of relaxation time. In addition we also present results on investigation of the relaxation phenomenon on a very local scale, where pinning and bowing of domain walls has been observed. We also show how this technique is used for obtaining quantitative information on piezoelectric constants and by engineering special structures, and how we realize ultrahigh values of piezoconstants. Last, we also show direct hysteresis measurements on nanoscale capacitors, where there is no observable loss of polarization in capacitors as small as 0.16 μm2 in area.

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Terahertz radiation emission from GaMnAs

Applied Physics Letters ◽

10.1063/1.2206154 ◽

2006 ◽

Vol 88 (22) ◽

pp. 221110 ◽

Cited By ~ 16

Author(s):

J. B. Héroux ◽

Y. Ino ◽

M. Kuwata-Gonokami ◽

Y. Hashimoto ◽

S. Katsumoto

Keyword(s):

Terahertz Radiation ◽

Radiation Emission

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