topological insulators tagged posts

A Monash University-led research team has discovered that a structure comprising an ultra-thin topological insulator sandwiched between two 2D ferromagnetic insulators becomes a large-bandgap quantum anomalous Hall insulator.

Such a heterostructure provides an avenue towards viable ultralow energy future electronics, or even topological photovoltaics.

Topological Insulator: The Filling in the Sandwich

In the researchers’ new heterostructure, a ferromagnetic material forms the ‘bread’ of the sandwich, while a topological insulator (ie, a material displaying nontrivial topology) ...

1, Bismuthene film interrupted at a step in the silicon carbide substrate viewed through a scanning tunnelling microscope. The film areas inevitably end at the substrate step and a conducting edge channel (white) occurs.
2. Schematic illustration of the conducting edge channels at the boundaries of the bismuthene film. The edge channels protect the spins against scattering and thereby allow loss-free and efficient spin-based data transmission.

It’s ultra-thin, electrically conducting at the edge due to quantum effects and insulating within – and all that at room temperature: Physicists from the University of Würzburg have developed a promising new material. The material class of topological insulators is presently the focus of international solids research...

In certain materials, light waves can change their direction of polarization. Credit: TU Wien

The ‘quantized magneto-electric effect’ has been demonstrated for the first time in topological insulators at TU Wien, which is set to open up new and highly accurate methods of measurement. A light wave sent through empty space always oscillates in the same direction. However, certain materials can be used to rotate the direction in which the light is oscillating in a magnetic field, ie ‘magneto-optical’ effect. Rather than switching the direction of the light wave continually,’topological insulators’ do so in quantum steps in clearly defined portions. The extent of these quantum steps depends solely on fundamental physical parameters, such as the fine-structure constant...

Artistic image of light trapped on the surface of a nanoparticle topological insulator. Credit: Vincenzo Giannini

New research suggests it is possible to create a new form of light by binding light to a single electron, combining the properties of both. According to the scientists from Imperial College London, the coupled light and electron would have properties that could lead to circuits that work with photons instead of electrons. It would also allow researchers to study quantum physical phenomena.

In normal materials, light interacts with a whole host of electrons present on the surface and within the material. But by using theoretical physics to model the behaviour of light and topological insulators, they have found that it could interact with just one electron on the surface...