Electrically driven amplification of terahertz acoustic waves in graphene.

In graphene devices, the electronic drift velocity can easily exceed the speed of sound in the material at moderate current biases. Under these conditions, the electronic system can efficiently amplify acoustic phonons, leading to an exponential growth of sound waves in the direction of the carrier flow. Here, we show that such phonon amplification can significantly modify the electrical properties of graphene devices.

Mechanically reconfigurable van der Waals devices via low-friction gold sliding.

Interfaces of van der Waals (vdW) materials, such as graphite and hexagonal boron nitride (hBN), exhibit low-friction sliding due to their atomically flat surfaces and weak vdW bonding. We demonstrate that microfabricated gold also slides with low friction on hBN. This enables the arbitrary post-fabrication repositioning of device features both at ambient conditions and in situ to a measurement cryostat.

Comment on "Investigation on the structure and thermoelectric properties of CuTe binary compounds" by Shriparna Mukherjee et al., Dalton Trans., 2019, 48, 1040.

The Raman spectra of copper tellurides are nearly unknown. This is due not only to the difficulty in obtaining single-phase specimens, but also to the low inelastic light scattering efficiency of CuTe. To date, only the Raman spectrum of the vulcanite phase, CuTe, has been both measured and calculated by density functional theory.

Crystalline structure, electronic and lattice-dynamics properties of NbTe.

Layered-structure materials are currently relevant given their quasi-2D nature. Knowledge of their physical properties is currently of major interest. Niobium ditelluride possesses a monoclinic layered-structure with a distortion in the tellurium planes.