Research Briefing in 2023

For a long time, spin–orbit coupling in bismuthates has been considered to be negligible; however, giant charge-to-spin conversion has now been observed in Ba(Pb,Bi)O₃-based heterostructures. These observations provide a path toward investigating the interplay of hidden spin–orbit phenomena and superconductivity.

A polymer-free method for stacking 2D materials has been demonstrated, using a cantilevered transfer support made from metallized silicon nitride. The assembly process, which is compatible with ultrahigh-vacuum operation, results in atomically clean and uniform interfaces.

A silicon photonics modulator design approach is proposed, in which the inductive networks and termination resistors are designed in conjunction with the optical phase shifter. A complementary metal–oxide–semiconductor (CMOS) silicon photonics transmitter developed with this approach achieved 112 gigabaud transmission with an energy efficiency better than 1 pJ per bit.

External-magnetic-field-free switching of the perpendicular magnetic anisotropy in magnetic layers is a prerequisite for the wide adoption of spintronic devices. This challenge could be met by the Weyl semimetal TaIrTe₄, which is now shown to generate an out-of-plane polarized spin current at room temperature.

Machine-learning-driven atomistic simulations are shown to describe phase-change materials on the length scale of real devices. This demonstration suggests that the atomic-scale design of phase-change architectures, programming conditions and full devices could be within reach.

The remarkable properties of graphene nanoribbons are promising for use in quantum technologies. To create quantum devices, however, individual nanoribbons must be contacted. This crucial step has now been demonstrated using single-walled carbon nanotubes as electrodes.

The use of topological spin structures is restricted by their limited scale, thermal stability or magnetic field requirements. A high-magnetic-field-assisted growth approach overcomes these limitations, enabling the construction of millimetre-scale meron lattices. These lattices were used to demonstrate chirality transfer from topologically protected quasiparticles to electrons and then photons.

Stacking a bilayer of chromium triiodide, a layered antiferromagnet, onto another with a twist angle gives rise to a moiré magnet with rich magnetic phases, including ferromagnetic and antiferromagnetic orders. The magnetic orders can be controlled through the twist angle, temperature and electrical gating, with the system also showing voltage-assisted magnetic switching.

The negative differential capacitance (NDC) of ferroelectrics could be used to reduce the energy consumption of ultra-scaled logic devices. An NDC phenomenon in ultrathin ferroelectric zirconium-doped hafnia is demonstrated. Field-effect transistors incorporating this ferroelectric in the gate stack display enhanced on-currents and reduced off-currents compared with conventional analogues, as well as tunable and enduring NDC.

Despite advances in speech processing systems, such as those used in voice-controlled devices, human hearing still outperforms technical systems in noisy and variable environments. To close this gap, a bioinspired acoustic sensor with integrated signal processing was developed — the dynamic microelectromechanical system (MEMS)-based cochlea.

A spoof surface plasmonic neural network with programmable weights and activation functions was proposed, which has the potential to achieve processing speeds close to the speed of light. This neural network was used to create a wireless communications system that can detect and process electromagnetic waves.

Conventional dielectric layers used in stretchable electronics are solution-processed, thick and have poor electrical performance compared with rigid, inorganic dielectrics. A stretchable nanometre-thick gate dielectric layer has been produced using large-area vacuum deposition. This material has excellent electrical, mechanical and chemical properties and could facilitate the development of high-performance wearable devices.

A skin-like sensory system, consisting of a substrate-less nanomesh strain sensor and an unsupervised meta-learning framework, enables the rapid recognition of various hand movements with minimal training and can work for any user. The device is able to complete various tasks, including virtual keyboard typing and object recognition.