RESUMO
The phonon magnetochiral effect consists of a nonreciprocity in the velocity or attenuation of acoustic waves when they propagate parallel and antiparallel to an external magnetic field. The first experimental observation of this effect in the bulk has been reported recently in a chiral magnet and ascribed to the hybridization between acoustic phonons and chiral magnons. Here, we predict a potentially measurable phonon magnetochiral effect of electronic origin in chiral Weyl semimetals. Caused by the Berry curvature and the orbital magnetic moment, this effect is enhanced for longitudinal phonons by the chiral anomaly.
RESUMO
We investigate wetting phenomena near graphene within the Dzyaloshinskii-Lifshitz-Pitaevskii theory for light gases of hydrogen, helium, and nitrogen in three different geometries where graphene is either affixed to an insulating substrate, submerged or suspended. We find that the presence of graphene has a significant effect in all configurations. When placed on a substrate, the polarizability of graphene can increase the strength of the total van der Waals force by a factor of 2 near the surface, enhancing the propensity towards wetting. In a suspended geometry unique to two-dimensional materials, where graphene is able to wet on only one side, liquid film growth becomes arrested at a critical thickness, which may trigger surface instabilities and pattern formation analogous to spinodal dewetting. The existence of a mesoscopic critical film with a tunable thickness provides a platform for the study of a continuous wetting transition, as well as the engineering of custom liquid coatings. These phenomena are robust to some mechanical deformations and are also universally present in doped graphene and other two-dimensional materials, such as monolayer dichalcogenides.
