The first 2D topological insulator consisting of a single element

May 16, 2023

(Nanowerk News) Researchers from the University of Twente proved that germanene, a two-dimensional material made of germanium atoms, behaves as a topological insulator. It is the first 2D topological isolator consisting of a single element. It also has the unique ability to switch between ‘on’ and ‘off’ states, comparable to a transistor. This can result in more energy efficient electronics.

These findings were published in Physical Review Letter (“Quantum Spin Hall States and Topological Phase Transitions in Germanene”). Scanning tunneling microscopy topography of a germanene honeycomb grid. (Image: University of Twente)

Topological insulators are materials with the unique property of isolating electricity on the inside while conducting electricity along the edges. Conductive edges allow electric current to flow without energy loss.

“Today, electronic devices lose a lot of energy in the form of heat, because material defects increase resistance. As a result, your phone becomes hot and uncomfortable, explains UT researcher Pantelis Bampoulis.

While scattering on defects is allowed in normal materials, at the edge of a 2D topological insulator, electron scattering on defects is prohibited due to a unique topological protection mechanism. Therefore, the electric current in a 2D topological insulator flows without wasting energy. This makes it more energy efficient than current electronic materials.

Create tightly

Germanene is a 2D topological isolator. “Today’s topological isolators consist of complex structures of various types of elements. Germanene is unique because it is made from only one element,” explained Bampoulis.

To make this interesting material, researchers melt germanium together with platinum. As the mixture cools, tiny layers of germanium atoms arrange into a honeycomb lattice over the germanium-platinum alloy. This layer of 2D atoms is called germanene. Artistic illustration of a non-dissipating edge channel in Germanene Artistic illustration of an edge channel without dissipation in germanene. (Image: Ella Marushchenko)

topology transistors

The researchers also found that the conducting properties of the material can be ‘turned off’ by applying an electric field. This property is unique to topological insulators. “The possibility to switch between ‘on’ and ‘off’ states adds an interesting application case for germanene”, says Bampoulis. This paved the way for designing topological field-effect transistors. These transistors can replace traditional transistors in electronic devices. Produce electronic goods that are no longer hot.

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