Dielectric properties of the hydrogen-bonded ferroelectric crystal KH_(2)PO_(4)(KDP)differ significantly from those of KD_(2)PO_(4)(DKDP).It is well established that deuteration affects the interplay of hydrogenbond s...
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Dielectric properties of the hydrogen-bonded ferroelectric crystal KH_(2)PO_(4)(KDP)differ significantly from those of KD_(2)PO_(4)(DKDP).It is well established that deuteration affects the interplay of hydrogenbond switches and heavy ion displacements that underlie the emergence of macroscopic polarization,but a detailed microscopic model is *** show that all-atompath integral molecular dynamics simulations can predict the isotope effects,revealing the microscopic mechanism that differentiates KDP and *** tunneling generates phosphate configurations that do not contribute to the *** low temperatures,these quantum dipolar defects are substantial in KDP but negligible in *** intrinsic defects explain why KDP has lower spontaneous polarization and transition entropy than *** prominent role of quantum fluctuations in KDP is related to the unusual strength of the hydrogen bonds and should be equally important in other crystals of the KDP family,which exhibit similar isotope effects.
In Weyl semimetals, Weyl points act as monopoles and antimonopoles of the Berry curvature, with a monopole-antimonopole pair producing a net-zero Berry flux. When inversion symmetry is preserved, the two-dimensional (...
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In Weyl semimetals, Weyl points act as monopoles and antimonopoles of the Berry curvature, with a monopole-antimonopole pair producing a net-zero Berry flux. When inversion symmetry is preserved, the two-dimensional (2D) planes that separate a monopole-antimonopole pair of Weyl points carry quantized Berry flux. In this work, we introduce a class of symmetry-protected Weyl semimetals which host monopole-antimonopole pairs of Weyl points that generate a dipolar Berry flux. Thus, both monopolar and dipolar Berry fluxes coexist in the Brillouin zone, which results in two distinct types of topologically nontrivial planes separating the Weyl points, carrying either a quantized monopolar or a quantized dipolar flux. We construct a topological invariant—the staggered Chern number—to measure the latter, and employ it to topologically distinguish between various Weyl points. Finally, through a minimal two-band model, we investigate physical signatures of bulk topology, including surface Fermi arcs, zero-energy hinge states, and response to insertion of a π-flux vortex.
We use density functional methods to identify the atomic configurations of H and D atoms trapped by O impurities embedded in bulk Nb. The O atoms are located at the octahedral position in the Nb body-centered cubic (B...
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We use density functional methods to identify the atomic configurations of H and D atoms trapped by O impurities embedded in bulk Nb. The O atoms are located at the octahedral position in the Nb body-centered cubic (BCC) lattice, and H (D) atoms tunnel between two degenerate tetrahedral sites separated by a mirror plane. Using nudged elastic band (NEB) methods, we calculate the double-well potential for O-H and O-D impurities and the wave functions and tunnel splittings for H and D atoms. Our results agree with those obtained from analysis of heat capacity and neutron scattering measurements on Nb with low concentrations of O-H and O-D.
Polyetheretherketone (PEEK) is a polymer widely used for artificial bone implants but exhibits a low affinity for bone tissue and lacks osteoconductivity and osseointegration. Because strontium (Sr) is known to enhanc...
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Achieving a good balance between the crystallinity and solubility is of great importance in the design of π-conjugated polymers. Here, we synthesized a series of terpolymers in which small fractions of a planar V-sha...
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We report that circularly polarized terahertz light pulses can drive chiral phonons, which then induce an effective quasi-static magnetic field on the order of 1 tesla to polarize the paramagnetic cerium fluoride. ...
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Linearly and circularly polarized phonons in monolayer WS2 are directly excited by resonant infrared pulses. The dynamics of coherent and incoherent chiral phonons are measured by time-resolved Raman spectroscopy and ...
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Fluorescence spectra of the 8PJ2→6PJ′2 (J and J′=3/2, 1/2) electric quadrupole transition of cesium atoms have been observed with a heated cesium vapor cell. We determined the ratio of the transition probabilities ...
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Fluorescence spectra of the 8PJ2→6PJ′2 (J and J′=3/2, 1/2) electric quadrupole transition of cesium atoms have been observed with a heated cesium vapor cell. We determined the ratio of the transition probabilities of 8PJ2→6PJ′2 to 8PJ2→5D3/22 by comparing their respective photon emission rates. The results are in good agreement with our theoretical calculations. These measurements provide crucial parameters for tests of the coherent amplification method and improve knowledge of cesium properties which are essential to dark matter detection through atomic transitions.
In recent years, self-assembling de novo-designed peptides have attracted increasing attention as materials for constructing submicrometer-scale structures. We have previously conducted structure-activity relationship...
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