Volume 18 Issue 3, March 2019

Topological structures have considerable potential in nanoelectronics and new device concepts. They are key to the design and understanding of novel functionalities in ferroic materials — that is, materials that have one or more types of built-in order such as magnetic, ferroelectric, ferroelastic and multiferroic materials.

Nian Sun, a professor at Northeastern University (Electrical and Computer Engineering Department), talks to Nature Materials about the potential applications of multiferroic materials, and issues associated with commercializing these technologies.

Microparticle debris from prosthetic implants has been shown to induce a type 2 inflammatory response through a Bruton’s tyrosine kinase-dependent signalling pathway.

Use of graphene in a transistor configuration offers an alternative to metal electrodes for the recording of ultraslow neural potentials that occur in neurologic diseases.

Multiferroic quantum criticality — associated with the merging of two distinct quantum critical points — is explored, with implications for fundamental physics and low-temperature applications.

A DNA nanodevice performs pathfinding search and computes the solution of two-dimensional DNA origami puzzles.

A hybrid state of photons and electronic excitations in semiconductor quantum wells shows nonlinear behaviour at the level of single or few quanta, thus opening the door to the realization of photonic nonlinear quantum devices employing semiconductor technologies.

Magnetoelectric multiferroics, where magnetic properties are manipulated by electric field and vice versa, could lead to improved electronic devices. Here, advances in materials, characterisation and modelling, and usage in applications are reviewed.

Two-photon correlation measurements in a resonantly excited fibre-cavity polariton system stay below the classical limit for zero time delay, suggesting quantum correlations between the polaritons.

Confined exciton–polaritons in semiconductor-based quantum wells can give rise to correlations slightly below the level of classical coincidence counts under resonant excitation, such that single or few polariton excitations are sufficient to modify the statistics of the radiation going through the system.

The phenomenology of multiferroic quantum criticality, where both ferroelectric and magnetic order parameters are tuned by quantum fluctuations, is drawn out. Non-thermal tuning parameters such as alloying and strain are explored and material realizations proposed.

Charge-frustration-induced melting of charge order is identified on a conducting organic triangular lattice, with a possible role of quantum effects.

Piezoelectrics convert force into electrical charge, and vice versa, but the coefficients that determine piezoelectric behaviour are constrained by crystal structure. Here, metamaterials are 3D printed that show arbitrary piezoelectric coefficients.

The investigation of a range of n- and p-doped small-molecule organic semiconductors reveals the role of the integer charge transfer complexes formed by host and dopant ions on conductivity and its thermal activation energy.

Asymmetric strain intrinsic to core/shell nanocrystals based on lattice-mismatched wurtzite semiconductors leads to suppression of spectral fluctuation, narrowing of photoluminescence linewidth and reduced blinking in colloidal nanocrystals.

Reversible high-voltage redox is a key component for electrochemical technologies from electrocatalysts to lithium-ion batteries. A point defect explanation for why anion redox occurs with local structural disordering and voltage hysteresis is proposed.

A chiral discotic triphenylene derivative spontaneously forms millimetre-sized assemblies with high structural order and fluid-like behaviour.

DNA-based nanodevices with decision-making and information-processing capabilities have been developed. Here, a DNA-based molecular navigation system that explores a DNA origami maze for all possible solutions is reported.

Arrays of graphene microtransistors are used to record infraslow cortical brain activity. The reduced signal drift and the array compatibility with optical imaging techniques make these devices useful for monitoring of brain physiology.

Microparticle wear debris from prosthetic implants following patient revision surgery is observed to induce a potent type 2 inflammatory response involving cytokine secretion by macrophages through a Bruton’s tyrosine kinase-dependent signalling pathway.