Quantum material to boost terahertz frequencies

By October 22, 2021October 25th, 2021ICN2

A study recently published in NPJ Quantum Materials provides new insight into the properties of topological insulators, materials that conduct electricity in a special way and hold the promise of novel circuits and faster mobile communications. This work was carried out by a research team led by Helmholtz-Zentrum Dresden-Rossendorf (HZDR) with involvement from ICN2 group leader Dr Klaas-Jan Tielrooij.

Topological insulators are a class of materials that have a special quantum property: on their surface they can conduct electricity almost loss-free while their interior functions as an insulator – no current can flow there. This opens up interesting prospects: topological insulators could form the basis for high efficiency electronic components, which makes them an interesting research field for physicists.

But a number of fundamental questions are still unanswered. What happens, for example, when you give the electrons in the material a “nudge” using specific electromagnetic waves – so-called terahertz radiation – thus generating an excited state? The electrons tend to release this extra-energy as quickly as possible, such as by heating up the crystal lattice surrounding them. In the case of topological insulators, however, it was previously unclear whether getting rid of this energy happened faster in the conducting surface than in the insulating core.

Under the leadership of Dr Sergey Kovalev, from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a research team from Germany, Spain, and Russia performed a series of experiments, using a special setup, to shed light on this enigma. They found out that the electrons in the surface became de-excited significantly faster than those in the interior of the material: apparently, they were able to transfer their energy to the crystal lattice immediately. These results are very relevant since they could lead to interesting developments in digital communication like WLAN and mobile communications.

This study has just been published in NPJ Quantum Materials. Dr Klaas-Jan Tielrooij, leader of the ICN2 Ultrafast Dynamics in Nanoscale Systems Group, took part in the work.

More information can be found on the ICN2 website