Spintronics Research Could Help Produce Chips Generating Less Heat

Some of the quantum properties of electrons in two-dimensional semiconductors have been successfully measured by EPFL researchers. This work carried out in the field of spintronics will one day be able to lead to chips that are not just smaller but produce less heat.

A group of spintronics researchers at EPFL is presently employing new materials in order to disclose more of the many competencies of electrons. The field of spintronics aims at tapping the quantum properties of "spin," the term frequently used for describing one of the essential properties of elementary particles - in this situation, electrons. This is considered to be among the most pioneering areas of research in today’s electronics.

Researchers working in the Laboratory of Nanoscale Electronics and Structures (LANES), which is monitored by Professor Andras Kis, succeeded in quantifying these quantum properties for a group of two-dimensional semiconductors known as transition metal dichalcogenides (TMDCs). Their research projects, recently featured in ACS Nano and also in Nature Communications, approve that materials such as graphene (C), tungsten diselenide (WSe2) and molybdenite (MoS2) offer, either alone or by merging some of their characteristics, new viewpoints for the field of electronics - perspectives capable of eventually leading to smaller chips that produce less heat.

With the methods we've recently developed, we've shown that it is possible to access the spin in these TMDC materials, quantify it and use it to introduce new functionalities.

Professor Andras Kis

All this takes place at a very small scale. The researchers must work with superior quality materials in order to evaluate these quantum properties.

If we want to examine certain characteristics of electrons, including their energy, we need to be able to watch them move over relatively long distances without there being too much dispersion or disruption.

Professor Andras Kis

In the form of waves

The method, developed by the researchers, allows them to attain samples of adequate quality both to note how electrons travel around in the form of waves and also to quantify their energy.

However, the LANES team also succeeded in evaluating another quantum property. Spins of electrons and holes in this kind of a 2D semiconductor can exist in one of two states, which are traditionally described as being oriented downward - spin down or upward - spin up. In each of these two states, their energy will be somewhat different. That is known as spin splitting, and the researchers have measured it for the very first time for electrons present in TMDC materials. The researchers, in the second publication, wrote about how they made use of the spin splitting in a TMDC to launch polarized spin currents in graphene without the use of a magnetic field.

These discoveries are considered to be a step forward for the growing field of spintronics, and they make it progressively likely that a diverse property of charge carriers – that is, spin, in addition to the electrical charge - will play a vital role in electronic devices of the future.