Topic
Spontelectrics
About: Spontelectrics is a research topic. Over the lifetime, 4 publications have been published within this topic receiving 66 citations.
Papers
TL;DR: A simplified theoretical model is developed which illustrates that electric fields can be understood in terms of dilution-dependent dipole orientation, and shows that dipole-dipole interactions are an essential ingredient for the creation of the spontelectric state.
Abstract: The recent discovery of a new class of solids displaying bulk spontaneous electric fields as high as 108 V m−1, so-called ‘spontelectrics’, poses fundamental and unresolved problems in solid state physics. The purpose of the present work is to delve more deeply into the nature of the interactions which give rise to the spontelectric effect in films of nitrous oxide (N2O), by observing the variation of the spontaneous field as the N2O molecules are physically removed from one another by dilution in Xe. Data, obtained using the ASTRID storage ring, are presented for films diluted by factors ξ = Xe/N2O of 0.9 to 67, at deposition temperatures of 38 K, 44 K and 48 K, where films are laid down by deposition from a gas mixture. Results show that the spontelectric field decreases as ξ increases and that at ξ = 67 for 44 K deposition, the spontelectric effect is absent. Reflection–absorption infrared spectroscopy (RAIRS) data are also reported, providing insight into the structure of Xe/N2O films and specifically showing that N2O remains dispersed in the Xe/N2O films prepared here. A simplified theoretical model is developed which illustrates that electric fields can be understood in terms of dilution-dependent dipole orientation. This model is used to reproduce experimental data up to an average molecular separation, s, of ≥1.25 nm apart, ∼4 times that associated with pure solid N2O. The disappearance of the spontelectric effect at larger average distances of separation, between s = 1.25 nm and s = 1.75 nm, is a phenomenon which cannot be described by any existing model but which shows that dipole–dipole interactions are an essential ingredient for the creation of the spontelectric state.
17 citations
TL;DR: It is shown that the novel properties of spontelectrics can be used to create composite sponteLECTrics, illustrating how electric fields in solid films may be structured on the nanoscale by combining layers of differentSpontelectric materials.
Abstract: A newly discovered class of molecular materials, so-called "spontelectrics", display spontaneous electric fields. Here we show that the novel properties of spontelectrics can be used to create composite spontelectrics, illustrating how electric fields in solid films may be structured on the nanoscale by combining layers of different spontelectric materials. This is demonstrated using the spontelectric materials nitrous oxide, toluene, isoprene, isopentane, and CF2Cl2. These yield a variety of tailored electric field structures, with individual layers harboring fields between 10(7) and 10(8) V/m. Fields may be of the same sign or of opposite sign, the latter enabling the creation of nanoscale potential wells. The formation of fields is followed using an established electron beam technique, employing the ASTRID synchrotron storage ring. The influence of temperature on heterolayer structures, displaying new Curie effects, and the nature of the interfacial region between different spontelectrics are also discussed.
17 citations
TL;DR: RAIRS data confirm that the behaviour of spontelectrics is governed by an expression for the degree of dipole orientation, which is continuous in temperature, but with a discontinuity in the derivative, and that the temperature of deposition associated with this discontinuity matches the temperature above which dipole order switches from the expected reduction with temperature to an increase with temperature.
Abstract: Using reflection-absorption infrared spectroscopy (RAIRS), we show that solids displaying spontaneous dipole orientation possess quite general non-local and non-linear characteristics, exemplified through their internal electric fields. The most graphic illustration of this, uncovered originally through electron beam studies, may be found in films of cis-methyl formate (cis-MF), for which data demonstrated the counter-intuitive property that the degree of dipole order in the film does not monotonically decrease as the temperature of deposition rises, but rather increases sharply above ∼77 K. Here we show how RAIRS provides independent evidence to support this conclusion. These new data confirm (i) that the behaviour of spontelectrics is governed by an expression for the degree of dipole orientation, which is continuous in temperature, but with a discontinuity in the derivative, and (ii) that the temperature of deposition associated with this discontinuity matches the temperature above which dipole order switches from the expected reduction with temperature to an increase with temperature.
9 citations
TL;DR: In this paper, the spontelectric effect was revealed using an instrument designed to measure scattering and capture of low energy electrons by molecular films and the properties of materials that display it were described.
Abstract: When dipolar gases are condensed at sufficiently low temperature onto a solid surface, they form films that may spontaneously exhibit electric fields in excess of 108 V/m. This effect, called the ‘spontelectric effect’, was recently revealed using an instrument designed to measure scattering and capture of low energy electrons by molecular films. In this review it is described how this discovery was made and the properties of materials that display the spontelectric effect, so-called ‘spontelectrics’, are set out. A discussion is included of properties that differentiate spontelectrics from ferroelectrics and other species in which spontaneous polarisation may be found. Spontelectric films may be composed of a number of quite mundane dipolar molecules that involve such diverse dipolar species as propane, nitrous oxide or methyl formate. Experimental results are presented for spontelectrics illustrating that the spontelectric field generally decreases monotonically with increasing deposition temperature, w...
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Performance Metrics
| Year | Papers |
|---|---|
| 2018 | 1 |
| 2014 | 2 |
| 2013 | 1 |