The wetting behaviour of surfaces is believed to be affected by van der Waals (vdW) forces; however, there is no clear demonstration of this. With the isolation of two-dimensional vdW layered materials it is possible to test this hypothesis. In this paper, we report the wetting behaviour of vdW heterostructures which include chemical vapor deposition (CVD) grown graphene, molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) on few layers of hexagon boron nitride (h-BN) and SiO₂/Si. Our study clearly shows that while this class of two-dimensional materials are not completely wetting transparent, there seems to be a significant amount of influence on their wetting properties by the underlying substrate due to dominant vdW forces. Contact angle measurements indicate that graphene and graphene-like layered transitional metal dichalcogenides invariably have intrinsically dispersive surfaces with a dominating London–vdW force-mediated wettability.

Molybdenum disulphide, a diamagnetic layered dichalcogenide solid, is found to show magnetic ordering at room temperature when exposed to a 2 MeV proton beam. The temperature dependence of magnetization displays ferrimagnetic behavior with a Curie temperature of 895 K. A disorder mode corresponding to a zone-edge phonon and a Mo valence higher than +4 has been detected in the irradiated samples using Raman and x-ray photoelectron spectroscopy, respectively. The possible origins of long-range magnetic ordering in irradiated MoS2 samples are discussed.

Control of magnetism in heterostructures: The interface between two different materials in a heterostructure can exhibit properties unique to either of the two materials alone. A well-known example is a conducting gas that forms when LaAlO ₃ is grown on SrTiO ₃ , but only if the LaAlO ₃ layer is at least four unit cells thick. Wang et al. report a similarly abrupt magnetic transition in a heterostructure formed by another oxide (LaMnO ₃ ) on the same SrTiO ₃ substrate. Even though bulk LaMnO ₃ is an antiferromagnet, when six or more unit-cell layers of it were deposited on SrTiO ₃ , it behaved like a ferromagnet. Science , this issue p. 716