Volume 19 Issue 6, June 2020

Father of modern ferroelectrics.

Two studies investigate the behaviour of localized interlayer excitons in van der Waals heterostructures, offering insights into their dipolar interactions and the effect of moiré trapping potentials for the design of quantum optical applications based on 2D materials.

Large-scale atomically thin metals can be stabilized through confinement epitaxy at graphene/SiC interface, which exhibit a gradient bonding type and are air stable, providing a compelling platform for quantum and optoelectronic technologies.

A high-speed, high-gain enhancement-mode ion-gated transistor shows promise for low-power chronically implanted bioelectronic systems.

Two independent studies describe the discovery of structurally pure cubic ice Ic made from either ice XVII or a high-pressure hydrogen hydrate.

While integrin-based adhesions are thought to underlie many aspects of cell response to localized tension, another matrix receptor, syndecan-4, has now been shown to act as a mechanosensor, which triggers cell-wide integrin activation and adhesion reinforcement.

This Review provides an overview of the advances in materials and device design that are enabling the realization of implantable electronic interfaces for long-term, multiplexed recording and stimulation of the brain and nervous system.

Flexoelectricity is the ability of materials to generate electricity upon bending. Here it is demonstrated that adding light to mechanical oscillation enhances effective flexoelectric coefficients by orders of magnitude, with the halide perovskites showing the largest coefficients.

Bi₂TeI is identified as a dual topological insulator. It is a weak topological insulator with metallic states at the (010) surfaces and a topological crystalline insulator at the (001) surfaces.

Interlayer exciton dynamics in a van der Waals heterostructure is found to be modulated by the twist angle between the atomically thin layers, elucidating the effect of moiré potentials on exciton motion and providing guidelines to design quantum photonics devices based on 2D materials.

Repulsive dipole–dipole interactions between localized interlayer excitons are shown to modify the optical response of van der Waals heterobilayers, forming the basis to obtain strong optical nonlinearity and excitonic many-body states in two-dimensional materials.

The optical properties of two species of localized interlayer excitons in a van der Waals heterostructure are shown to depend on their spin–valley–layer configuration, enabling the identification of the moiré atomic registry and offering insights for engineering quantum states in two-dimensional materials.

Single-crystal 2D metals are stabilized at the interface between epitaxial graphene and silicon carbide, with strong internal gradients in bonding character. The confined 2D metals demonstrate compelling superconducting properties.

The application of metal fluorides as cathodes for lithium ion batteries has been hindered by inadequate understanding of their electrochemical capabilities. Reversible conversion reaction in iron fluoride nanocrystals is shown to be due to topotactic cation diffusion and nucleation of metallic particles.

Unlike dynamic control of electrical conductivity, tuning thermal conductivity by means of electric potential is challenging. Electrochemically induced phase transition control of oxygen and proton concentration in a SrCoO_x oxide provides a way to tune bi-directionally thermal conductivity.

Structurally pure cubic ice Ic is obtained from the controlled heating of D₂O ice XVII.

A mechanism of cell response to localized tension shows that syndecan-4 synergizes with EGFR to elicit a mechanosignalling cascade that leads to adaptive cell stiffening through PI3K/kindlin-2 mediated integrin activation.

Internal ion-gated organic electrochemical transistors operating in enhancement mode are shown to record electrophysiological signals in vivo, with a speed and sensitivity that enable the detection of action potentials from individual neurons.

Litao Sun, Yongming Tang and Wei Zuo reflect on their experience of nationwide distance learning in China’s universities during the COVID-19 outbreak.