2,580 research outputs found
Insight into perovskite antiferroelectric phases: Landau theory and phase field study
Understanding the appearance of commensurate and incommensurate modulations
in perovskite antiferroelectrics (AFEs) is of great importance for material
design and engineering. The dielectric and elastic properties of the AFE domain
boundaries are lack of investigation. In this work, a novel Landau theory is
proposed to understand the transformation of AFE commensurate and
incommensurate phases, by considering the coupling between the oxygen
octahedral tilt mode and the polar mode. The derived relationship between the
modulation periodicity and temperature is in good agreement with the
experimental results. Using the phase field study, we show that the
polarization is suppressed at the AFE domain boundaries, contributing to a
remnant polarization and local elastic stress field in AFE incommensurate
phases
Probing the states through radiative decays
In this work, we have adopted the spin rearrangement scheme in the heavy
quark limit and extensively investigated three classes of the radiative decays:
, , , corresponding to the
electromagnetic transitions between one molecular state and bottomonium, one
bottomonium and molecular state, and two molecular states respectively. We also
extend the same formalism to study the radiative decays of the molecular states
with hidden charm. We have derived some model independent ratios when the
initial or final states belong to the same spin flavor multiplet. Future
experimental measurement of these ratios will test the molecular picture and
explore the underlying structures of the states.Comment: 21 pages, 10 tables Accepted by Phys.Rev.
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