Theory of exciton transport in molecular crystals strongly coupled to a cavity: A temperature-dependent variational approach

Spin and valley degrees of freedom in materials without inversion symmetry promise previously unknown device functionalities, such as spin-valleytronics. Control of material symmetry with electric fields (ferroelectricity), while breaking additional symmetries, including mirror symmetry, could yield phenomena where chirality, spin, valley, and crystal potential are strongly coupled. Here we report the synthesis of a halide perovskite semiconductor that is simultaneously photoferroelectricity switchable and chiral. Spectroscopic and structural analysis, and first-principles calculations, determine the material to be a previously unknown low-dimensional hybrid perovskite (R)-(−)-1-cyclohexylethylammonium/(S)-(+)-1 cyclohexylethylammonium) PbI3. Optical and electrical measurements characterize its semiconducting, ferroelectric, switchable pyroelectricity and switchable photoferroelectric properties. Temperature dependent structural, dielectric and transport measurements reveal a ferroelectric-paraelectric phase transition. Circular dichroism spectroscopy confirms its chirality. The development of a material with such a combination of these properties will facilitate the exploration of phenomena such as electric field and chiral enantiomer–dependent Rashba-Dresselhaus splitting and circular photogalvanic effects.

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The variational approach to the Glashow–Weinberg–Salam model

Canadian Journal of Physics ◽

10.1139/p87-049 ◽

1987 ◽

Vol 65 (4) ◽

pp. 395-402 ◽

Cited By ~ 4

Author(s):

R. Manka ◽

J. Sladkowski

Keyword(s):

Phase Transition ◽

Effective Potential ◽

Variational Approach ◽

Canonical Quantization ◽

Temperature Dependent ◽

Model Based

The variational approach to the Glashow–Weinberg–Salam model, based on canonical quantization, is presented. It is shown that taking into consideration the Becchi–Rouet–Stora symmetry leads to the correct, temperature-dependent, effective potential. This generalization of the Weinberg–Coleman potential leads to a phase transition of the first kind.

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Temperature-dependent isomorphous phase transition studies in molecular crystals of 2,4,4′-trimethoxybenzophenone

Journal of Molecular Structure ◽

10.1016/j.molstruc.2009.11.007 ◽

2010 ◽

Vol 964 (1-3) ◽

pp. 31-38 ◽

Cited By ~ 3

Author(s):

Hoong-Kun Fun ◽

Ching Kheng Quah ◽

Samuel Robinson Jebas ◽

Lye-Hock Ong

Keyword(s):

Phase Transition ◽

Molecular Crystals ◽

Temperature Dependent ◽

Transition Studies

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Strongly coupled thermal and chemical expansion in the perovskite oxide system Sr(Ti,Fe)O3−α

Journal of Materials Chemistry A ◽

10.1039/c4ta05247a ◽

2015 ◽

Vol 3 (7) ◽

pp. 3602-3611 ◽

Cited By ~ 27

Author(s):

Nicola H. Perry ◽

Jae Jin Kim ◽

Sean R. Bishop ◽

Harry L. Tuller

Keyword(s):

Energy Conversion ◽

Oxide System ◽

Perovskite Oxide ◽

Oxygen Stoichiometry ◽

Temperature Dependent ◽

Chemical Expansion ◽

Strongly Coupled ◽

Expansion Coefficients ◽

Energy Conversion Devices ◽

First Time

To evaluate stability in energy conversion devices, thermal and chemical expansion coefficients (CTE, CCE) of Sr(Ti,Fe)O3−α were measured and deconvoluted for the first time, revealing an oxygen stoichiometry-dependent CTE and temperature-dependent CCE.

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Observations of the temperature dependent response of ozone to NO<sub>x</sub> reductions in the Sacramento, CA urban plume

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-6945-2011 ◽

2011 ◽

Vol 11 (14) ◽

pp. 6945-6960 ◽

Cited By ~ 27

Author(s):

B. W. LaFranchi ◽

A. H. Goldstein ◽

R. C. Cohen

Keyword(s):

Ozone Production ◽

Metropolitan Region ◽

Temperature Dependent ◽

Strongly Coupled ◽

Detailed Chemistry ◽

Mixing Ratios ◽

Current Trends ◽

Biogenic Voc ◽

Steady State Model ◽

Urban Plume

Abstract. Observations of NOx in the Sacramento, CA region show that mixing ratios decreased by 30 % between 2001 and 2008. Here we use an observation-based method to quantify net ozone (O3) production rates in the outflow from the Sacramento metropolitan region and examine the O3 decrease resulting from reductions in NOx emissions. This observational method does not rely on assumptions about detailed chemistry of ozone production, rather it is an independent means to verify and test these assumptions. We use an instantaneous steady-state model as well as a detailed 1-D plume model to aid in interpretation of the ozone production inferred from observations. In agreement with the models, the observations show that early in the plume, the NOx dependence for Ox (Ox = O3 + NO2) production is strongly coupled with temperature, suggesting that temperature-dependent biogenic VOC emissions and other temperature-related effects can drive Ox production between NOx-limited and NOx-suppressed regimes. As a result, NOx reductions were found to be most effective at higher temperatures over the 7 year period. We show that violations of the California 1-h O3 standard (90 ppb) in the region have been decreasing linearly with decreases in NOx (at a given temperature) and predict that reductions of NOx concentrations (and presumably emissions) by an additional 30 % (relative to 2007 levels) will eliminate violations of the state 1 h standard in the region. If current trends continue, a 30 % decrease in NOx is expected by 2012, and an end to violations of the 1 h standard in the Sacramento region appears to be imminent.

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Simulation of exciton transport in binary molecular crystals and comparison with experiments in chemically mixed crystals

Chemical Physics ◽

10.1016/0301-0104(95)96875-j ◽

1995 ◽

Vol 197 (2) ◽

pp. 139-146 ◽

Cited By ~ 1

Author(s):

F. Otto ◽

E. Tränkle ◽

C. von Borczyskowski

Keyword(s):

Molecular Crystals ◽

Mixed Crystals ◽

Exciton Transport ◽

Comparison With Experiments

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Coupled Electro-Thermal Mechanical Analyses for SMM Actuators Development

Microelectromechanical Systems ◽

10.1115/imece2004-61916 ◽

2004 ◽

Author(s):

C. Channy Wong ◽

Randy R. Lober ◽

Jason D. Hales

Keyword(s):

Electrical Resistivity ◽

Temperature Distribution ◽

Joule Heating ◽

Temperature Dependent ◽

Strongly Coupled ◽

Mechanical Responses ◽

Thermal Actuators ◽

Micro Actuators ◽

And Performance

A coupled-physics analysis code has been developed to simulate the electrical, thermal, and mechanical responses of surface micromachined (SMM) actuators. Our objective is to optimize the design and performance of these micro actuators. Since many new designs of these electro-thermal actuators have shuttles or platforms between beams, calculating the local Joule heating requires a multi-dimensional electrostatics analysis. Moreover, the electrical solution is strongly coupled to the temperature distribution since the electrical resistivity is temperature dependent. Thus, it is essential to perform a more comprehensive simulation that solves the coupled electrostatics, thermal, and mechanical equations. Results of the coupled-physics analyses will be presented.

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