New quantum materials offer novel route to 3-D electronic devices

November 7, 2017, Academy of Finland
(a) By local manipulation of material parameters, it is possible to tune the properties of charge carriers in Weyl semimetals; (b) With suitable local manipulation of material parameters, one can tailor the carrier motion and design novel electronic devices such as the electron lens, which focuses the incoming carriers. Credit: Academy of Finland

Researchers have shown how the principles of general relativity open the door to novel electronic applications such as a three-dimensional electron lens and electronic invisibility devices. In a new study funded by the Academy of Finland, Aalto University researchers Alex Westström and Teemu Ojanen propose a method to go beyond special relativity and simulate Einstein's theory of general relativity in inhomogeneous Weyl semimetals. The theory of Weyl metamaterials combines ideas from solid-state physics, particle physics and cosmology and points a way to fabricate metallic designer materials where charge carriers move like particles in curved space-time.

The researchers propose Weyl metamaterials, a generalisation of Weyl semimetals, that enable new types of electronic devices through engineering.

"The systems we introduced offer a route to make the move as if they were living in a curved geometry, providing a tabletop laboratory for simulating curved-space quantum physics and certain cosmological phenomena," Alex Westström explains.

Weyl semimetals are an example of recently discovered quantum materials that have received a lot of attention. Charge carriers in these materials behave as if they were massless particles moving at the speed of light.

"We discovered that Weyl metamaterials may serve as a platform for exotic electronic devices such as the 3-D electron lens, where the trajectories of charge carriers are focused much like beams of light in an optical lens," Teemu Ojanen says.

The electric conduction in Weyl semimetals reflects the physics of Einstein's special theory of . Nevertheless, also assumes an absence of gravity, which Einstein formulated as a geometry of space-time.

The theory of Weyl metamaterials also paves the way for fundamentally new electronics applications, for instance, the development of electronic invisibility devices. The key idea behind the potential applications is an artificially created curved geometry, which bends the motion of charge carriers in a controlled way.

"In optics, it's been known for centuries that light always chooses the quickest trajectory. In curved geometry, the quickest path doesn't look like a straight line for those watching from outside. The functionality of optical invisibility devices, where the beams of light bypass a hidden object, is in fact based on the application of curved-space geometry. It would be a breakthrough in fundamental research to achieve a similar functionality in electronic systems," Ojanen adds.

Explore further: Scientists explain the way Weyl particles 'dance' on crystal surface

More information: Alex Westström et al. Designer Curved-Space Geometry for Relativistic Fermions in Weyl Metamaterials, Physical Review X (2017). DOI: 10.1103/PhysRevX.7.041026

Related Stories

New material discovery allows study of elusive Weyl fermion

August 12, 2016

Researchers at the U.S. Department of Energy's Ames Laboratory have discovered a new type of Weyl semimetal, a material that opens the way for further study of Weyl fermions, a type of massless elementary particle hypothesized ...

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

Weyl fermions exhibit paradoxical behavior

May 23, 2017

Theoretical physicists have found Weyl fermions to exhibit paradoxical behavior in contradiction to a 30-year-old fundamental theory of electromagnetism. The discovery has possible applications in spintronics. The study ...

Recommended for you

X-rays reveal chirality in swirling electric vortices

January 16, 2018

Scientists used spiraling X-rays at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) to observe, for the first time, a property that gives handedness to swirling electric patterns – dubbed ...

Slow 'hot electrons' could improve solar cell efficiency

January 16, 2018

Photons with energy higher than the band gap of the semiconductor absorbing them give rise to what are known as hot electrons. The extra energy in respect to the band gap is lost very fast, as it is converted into heat and ...

Quan­tum physics turned into tan­gi­ble re­al­ity

January 16, 2018

ETH physicists have developed a silicon wafer that behaves like a topological insulator when stimulated using ultrasound. They have thereby succeeded in turning an abstract theoretical concept into a macroscopic product.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.