Letters in 2021

MoS₂/hBN/graphene van der Waals heterostructures with a clean interface and optimized barrier height and gate coupling ratio enable the realization of ultrafast non-volatile flash memory.

In situ electrostatic control of two-dimensional superconductivity is commonly limited due to large charge carrier densities. Now, by means of local gates, electrostatic gating can define a Josephson junction in a magic-angle twisted bilayer graphene device, a single-crystal material.

A 1/3 power law between thermal conductivity and length of a NbSe₃ nanowire is observed, pointing towards a superdiffusive heat transport regime.

While two-dimensional semiconductors enable the investigation of light–matter interactions in low dimensions, a link to magnetic order has so far remained elusive. Now, the antiferromagnetic insulator NiPS₃ is found to exhibit excitons with strong linear polarization that are coupled to the zigzag antiferromagnetic order.

A measurement protocol allows the conductance and the thermocurrent of a single molecule to be determined simultaneously.

The resonance of highly doping lanthanide ions in NaYF₄ nanocrystals enhances the permittivity and polarizability of nanocrystals, leading to enhanced optical trapping forces by orders of magnitude, bypassing the trapping requirement of refractive index mismatch.

Dielectric patterning allows tunable anisotropy in high-mobility one-dimensional graphene electrostatic superlattices.

Stochastic orbital dynamics of individually coupled Co atoms on black phosphorus enables the realization of a Boltzmann machine capable of self-adaption.

High efficiency, coherence and indistinguishability are key requirements for the application of single-photon sources for quantum technologies, but hard to achieve concurrently. A gated quantum dot in an open, tunable microcavity now can create single photons on-demand with an end-to-end efficiency of 57%, preserving coherence over microsecond-long trains of single photons.

Broken inversion symmetry in a type-II Weyl semimetal TaIrTe₄ enables observation of the room-temperature nonlinear Hall effect as well as wireless radiofrequency rectification.

Increasing the fatigue life of shape memory alloys often compromises other mechanical properties such as yield strength and plastic deformation behaviour. Introducing a mixed nanostructure of crystalline and amorphous phases can enable superelasticity in NiTi micropillars with recoverable strain of 4.3%, yield strength of 2.3 GPa and 10⁸ reversible-phase transition cycles under a stress of 1.8 GPa.

Spin–orbit torque in heavy metal/ferromagnet heterostructures is promising for all-electric control of magnetic memory, but has so far required an additional symmetry breaking in the design to switch perpendicular magnetization. Instead, a low symmetry at the interface can give rise to out-of-plane spin torque and switch the magnetization deterministically.

Typically, quasiparticles are injected into superconductors at energies comparable to the pairing energy in order to gain insights into quasiparticle dynamics. Tunnelling spectroscopy of a mesoscopic superconductor under high electric field now provides insights into a regime where electrons impinge with 10⁶ times the pairing energy.