As smartphones get smarter and computers compute faster, researchers actively search for ways to speed up the processing of information. Now, scientists at Princeton University have made a step forward in developing a new class of materials that could be used in future technologies.
They have discovered a new quantum effect that enables electrons — the negative-charge-carrying particles that make today's electronic devices possible — to dash through the interior of these materials with very little resistance.
"This is a big deal," Hasan said. "It means the electrons can flow quite easily in the material and many more exotic quantum effects can now be studied. That just wasn't possible in the past."
The most promising application for these materials may be for a proposed "topological quantum computer" based on novel electronics that would use a property of electrons known as "spin" to do calculations and transmit information.
The quantum behavior in this new class of materials has led them to be called "topological Dirac semi-metals" in reference to English quantum physicist and 1933 Nobel Prize winner Paul Dirac, who noted that electrons could behave like light. Semi-metals that are "topological" are ones that retain their spatial electronic properties — and their speedy electrons — even when deformed by certain types of stretching and twisting.
"This is a big deal..."M. Zahid Hasan, a professor of physics at Princeton, who led the discovery.
The speeds achieved by these electrons have led to comparisons to another novel electronic material, graphene. The new class of materials has the potential to be superior to graphene in some aspects, Hasan said, because graphene is a single layer of atoms in which electrons can flow only in two dimensions. Cadmium arsenide permits electrons to flow in three dimensions. The new study redefines what it means to be a topological material, according to the researcher.
"The term topological insulator is now quite famous, and the yet term 'insulator' means that there are no electrons flowing in the bulk of the material," Xu said. "Our study shows that electrons are flowing in the bulk of the material, so clearly cadmium arsenide is not an insulator, but it is still topological in nature, so this is a totally new type of quantum matter," he said.
The team made the discovery using a technique called angle-resolved photoemission spectroscopy. The researchers shined a very powerful X-ray beam — using a particle accelerator at the Advanced Light Source at Lawrence Berkeley National Laboratory — onto the surface of the material then monitored the electrons as they were knocked out of the interior.
"When the electron comes out, we measure its energy and velocity, and what we found is that electrons coming out of the cadmium arsenide had measurements that were similar to what is seen in particles that are massless," Neupane said.
This story is reprinted from material from Princeton University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.