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Galvanic replacement (GR) of monometallic nanoparticles (NPs) provides a versatile route to interesting bimetallic nanostructures, with examples such as nanoboxes, nanocages, nanoshells, nanorings, and heterodimers reported. The replacement of bimetallic templates by a more noble metal can generate trimetallic nanostructures with different architectures, where the specific structure has been shown to depend on the relative reduction potentials of the participating metals and lattice mismatch between the depositing and template metal phases. Now, the role of reaction stoichiometry is shown to direct the overall architecture of multimetallic nanostructures produced by GR with bimetallic templates. Specifically, the number of initial metal islands deposited on a NP template depends on the reaction stoichiometry. This outcome was established by studying the GR process between intermetallic PdCu (i-PdCu) NPs and either AuCl 2 − (Au 1+ ) or AuCl 4 − (Au 3+ ), producing i-PdCu–Au heterostructures. Significantly, multiple Au domains form in the case of GR with AuCl 2 − while only single Au domains form in the case of AuCl 4 − . These different NP architectures and their connection to reaction stoichiometry are consistent with Stranski–Krastanov (SK) growth, providing general guidelines on how the conditions of GR processes can be used to achieve multimetallic nanostructures with different defined architectures. 

In this paper, we prove an Azuma-Hoeffding-type inequality in several classical models of random configurations by a Ricci curvature approach. Adapting Ollivier’s work on the Ricci curvature of Markov chains on metric spaces, we prove a cleaner form of the corresponding concentration inequality in graphs. Namely, we show that for any Lipschitz function f on any graph (equipped with an ergodic random walk and thus an invariant distribution ν) with Ricci curvature at least κ > 0, we have ν (|f − Eνf| ≥ t) ≤ 2 exp(−t^2κ/7). 

Abstract Hybrid magnonic systems are a newcomer for pursuing coherent information processing owing to their rich quantum engineering functionalities. One prototypical example is hybrid magnonics in antiferromagnets with an easy-plane anisotropy that resembles a quantum-mechanically mixed two-level spin system through the coupling of acoustic and optical magnons. Generally, the coupling between these orthogonal modes is forbidden due to their opposite parity. Here we show that the Dzyaloshinskii–Moriya-Interaction (DMI), a chiral antisymmetric interaction that occurs in magnetic systems with low symmetry, can lift this restriction. We report that layered hybrid perovskite antiferromagnets with an interlayer DMI can lead to a strong intrinsic magnon-magnon coupling strength up to 0.24 GHz, which is four times greater than the dissipation rates of the acoustic/optical modes. Our work shows that the DMI in these hybrid antiferromagnets holds promise for leveraging magnon-magnon coupling by harnessing symmetry breaking in a highly tunable, solution-processable layered magnetic platform. 

Abstract Chiral perovskite nanocrystals have emerged as an interesting chiral excitonic platform that combines both structural flexibility and superior optoelectronic properties. Despite several recent demonstrations of optical activity in various chiral perovskite nanocrystals, efficient circularly polarized luminescence (CPL) with tunable energies remains a challenge. The chirality imprinting mechanism as a function of perovskite nanocrystal dimensionality remains elusive. Here, atomically thin inorganic perovskite nanoplatelets (NPLs) are synthesized with precise control of layer thickness and are functionalized by chiral surface ligands, serving as a unique platform to probe the chirality transfer mechanism at the organic/perovskite interface. It is found that chirality is successfully imprinted into mono‐, bi‐, and tri‐layer inorganic perovskite NPLs, exhibiting tunable circular dichroism (CD) and CPL responses. However, chirality transfer decreases in thicker NPLs, resulting in decreased CD and CPL dissymmetry factors for thicker NPLs. Aided by large‐scale first‐principles calculations, it is proposed that chirality transfer is mainly mediated through a surface distortion rather than a hybridization of electronic states, giving rise to symmetry breaking in the perovskite lattice and spin‐split conduction bands. The findings described here provide an in‐depth understanding of chirality transfer and design principles for distorted‐surface perovskites for chiral photonic applications. 

Ribozymes synthesize proteins in a highly regulated local environment to minimize side reactions caused by various competing species. In contrast, it is challenging to prepare synthetic polypeptides from the polymerization of N -carboxyanhydrides (NCAs) in the presence of water and impurities, which induce monomer degradations and chain terminations, respectively. Inspired by natural protein synthesis, we herein report the preparation of well-defined polypeptides in the presence of competing species, by using a water/dichloromethane biphasic system with macroinitiators anchored at the interface. The impurities are extracted into the aqueous phase in situ, and the localized macroinitiators allow for NCA polymerization at a rate which outpaces water-induced side reactions. Our polymerization strategy streamlines the process from amino acids toward high molecular weight polypeptides with low dispersity by circumventing the tedious NCA purification and the demands for air-free conditions, enabling low-cost, large-scale production of polypeptides that has potential to change the paradigm of polypeptide-based biomaterials.