Atomically thin TaS2 devices. (a) Ball and stick model of the crystal structure of the 2H polytype of TaS2. The dashed prism encloses the content of a single unit cell and the metal coordination geometry is highlighted by the red polyhedron. (b) Atomic force microscopy image of two devices fabricated on a 3.5-nm 2H-TaS2 flake. The scale bar is 4 μm in length. The full colour scale of the topograph corresponds to a height of 100 nm. (c) Line profile of the flake taken at the location of the white dotted line in b.
Uni of Valencia researchers show superconducting state can be maintained even when the material in question is reduced from 3 to 2 dimensions, making the efficiency gains needed for technologies like those underlying the frictionless train possible. It also paves the way for the miniaturisation of ultrasensitive magnetic field detectors.
Since its discovery in 1911, one of the issues that has most intrigued scientists is whether it is possible to maintain the superconducting state even when the material is reduced from three to two dimensions. Intuitively we expect that it would be more difficult to stabilise the superconducting state when the dimensionality is reduced. The researchers studied layered materials similar to graphene, but which become superconductors when cooled to low temperatures. Specifically, they have studied the electrical properties of a large family of layered materals known as metal dichalcogenides.
As with graphene, these materials are made up of individual atom layers that can be easily exfoliated, which makes it possible to obtain sheets of different thicknesses, made up of a specific number of layers. In one of the compounds from this family, tantalum disulphide (TaS2), they found that, contrary to expectations, the temperature at which it becomes superconducting increases as the number of layers is reduced, ie it is indeed maintained at the two-dimensional limit. http://ruvid.org/ri-world/valencian-scientists-explore-superconductivity-at-the-two-dimensional-limit/ Atomically thin TaS2 devices
http://www.nature.com/ncomms/2016/160317/ncomms11043/full/ncomms11043.html
Recent Comments