We propose that domain walls formed in a classical Ginzburg–Landau model can exhibit topologically stable but thermodynamically metastable states. This proposal relies on Allen–Cahn’s assertion that ...the velocity of domain wall is proportional to the mean curvature at each point. From this assertion we speculate that domain wall behaves like a rubber band that can winds the background geometry in a nontrivial way and can exist permanently. We numerically verify our proposal in two and three spatial dimensions by using various boundary conditions. It is found that there are possibilities to form topologically stable domain walls in the final equilibrium states. However, these states have higher free energies, thus are thermodynamically metastable. These metastable states that are protected by topology could potentially serve as storage media in the computer and information technology industry.
•Domain walls formed in a classical Ginzburg–Landau model can exhibit topologically stable but thermodynamically metastable states.•Domain wall behaves like a rubber band that can winds the background geometry in a nontrivial way and can exist permanently.•There are possibilities to form topologically stable domain walls in the final equilibrium states.
Pressure engineering can access novel optoelectronic properties and crystal structures in halide perovskite materials with soft lattice. However, such pressure‐induced phenomena are commonly realized ...under large pressure or difficult to retain at atmospheric pressure, thus severely hindering their prospects in practical applications. Herein, the pressure‐treated Mn‐doped/undoped Cs2NaBiCl6 exhibits a largely retained bandgap narrowing of 12.2% relative to its initial state via compression–decompression cycles, along with durable stability at ambient conditions. This abnormal behavior is attributed to the disordered arrangement of inorganic NaCl65−/BiCl63− octahedra, which occurs in the metastable state of double perovskites from structural reconstruction during decompression processes, and is accompanied by a characteristic of long‐range order and short‐range disorder. A remarkable pressure‐induced emission enhancement from Mn2+ ions is discovered upon modest compression, especially at <0.5 GPa, which results from the increased energy transfer efficiency from Bi3+ to Mn2+ ions owing to more overlapped electronic wave functions from each other. This work can be extended to the design and synthesis of new semiconductor materials with enhanced optoelectronic properties.
Retainable bandgap narrowing and enhanced Mn2+ emission with remarkable piezochromism are achieved in sodium–bismuth double perovskites by carrying out pressure engineering, mapping a new route to improve the optoelectronic properties of double perovskites by introducing chemical pressure and lattice strain, or constructing metastable states for practical applications in the future.
Metastable molecular fluid hydrogen at high pressures Norman, Genri E.; Saitov, Ilnur M.; Sartan, Roman A.
Contributions to plasma physics (1988),
July 2019, 2019-07-00, 20190701, Letnik:
59, Številka:
6
Journal Article
Recenzirano
Warm dense hydrogen is studied in the region of fluid–fluid phase transition within the framework of the density functional theory. We report a procedure of obtaining metastable states and calculate ...the equation of state. Metastable states are diagnosed by pair correlation functions and values of conductivity. We obtain a strong overlapping through the density of metastable and equilibrium branches of pressure isotherms. This indicates the plasma nature of the phase transition.
Supramolecular assemblies with well-defined structural attenuation toward varied functional implications are an emerging area in mimicking natural biomaterials. In that regard, the redox ...stimuli-responsive ferrocene moiety can reversibly change between a nonpolar ferrocenyl and polar ferrocenium cation that endows interesting modular features to the building blocks with respect to self-assembly/disassembly. We design a series of ferrocene anchored peptide fragment N VFFAKK C using hydrophobic alkyl spacers of different chain lengths. Increasing the spacer length between the redox-responsive and self-assembling motifs increases the propensity to form robust nanofibers, which can be physically cross-linked to form hydrogels. The controlled redox response of the ferrocene moiety tandem with pH control provides access to structural control over the peptide nanostructures and tunable mechanical strengths. Further, such redox-sequestered dormant states hinder the spontaneous nucleation process that we exploit toward seeded supramolecular polymerization to form block cofibers composed of redox-responsive periphery and nonresponsive cores. Finally, such redox sequestration of peptide self-assembly renders an on–off piezoelectric response for potential utilization in peptide bioelectronics.
The quantum–classical transition of wave packet barrier scattering is investigated using a hydrodynamic description in the framework of a nonlinear Schrödinger equation. The nonlinear equation ...provides a continuous description for the quantum–classical transition of physical systems by introducing a degree of quantumness. Based on the transition equation, the transition trajectory formalism is developed to establish the connection between classical and quantum trajectories. The quantum–classical transition is then analyzed for the scattering of a Gaussian wave packet from an Eckart barrier and the decay of a metastable state. Computational results for the evolution of the wave packet and the transmission probabilities indicate that classical results are recovered when the degree of quantumness tends to zero. Classical trajectories are in excellent agreement with the transition trajectories in the classical limit, except in some regions where transition trajectories cannot cross because of the single-valuedness of the transition wave function. As the computational results demonstrate, the process that the Planck constant tends to zero is equivalent to the gradual removal of quantum effects originating from the quantum potential. This study provides an insightful trajectory interpretation for the quantum–classical transition of wave packet barrier scattering.
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