Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Laser pulses create topological state in graphene

06.11.2019

Discovering ways to control the topological aspects of quantum materials is an important research frontier because it can lead to desirable electrical and spin transport properties for future device technologies. Now MPSD scientists have discovered a pioneering laser-driven approach to generate a topological state in graphene. Their work has just been published in Nature Physics.

In topological materials, electrons experience a twisted world. Instead of simply moving straight ahead when feeling a force, they may be pushed sideways. In such a material current actually flows orthogonally to an applied voltage.


Topological quantum states in graphene induced by light

Benedikt Schulte, MPSD

The basic model describing the effect was developed by Duncan Haldane in the late 1980s, but even its inventor was skeptical that it could ever be implemented in a real material.

Nevertheless, elaborate chemical synthesis eventually allowed for very similar effects to be observed, sparking a technological revolution - and eventually earning Haldane the 2016 Nobel Prize in Physics.

Topological transport is usually induced in materials by applying strong magnetic fields or by crafting compounds with strong spin-orbit coupling. Researchers in Andrea Cavalleri’s group at the MPSD have now demonstrated that a coherent interaction with circularly polarized light can also induce topological electrical currents in the material graphene.

The team’s radically different approach consists of illuminating graphene with a strong, circularly polarized laser pulse, whose electric field drives electrons in loops. When the material is illuminated, it suddenly behaves like a topological material. It returns to its normal state once the pulse is gone.

Whilst this mechanism had been tested in simulations, it was entirely unclear whether it would work in the more complicated context of real solids – and whether it would be possible to detect it.

To prove their discovery, the physicists had to show currents flowing in a direction orthogonal to an applied voltage. However, there was a major challenge: "As the effect persists only for about a millionth of a millionth of a second, we had to develop a novel type of electronic circuit to measure this," says lead author James McIver.

The result was an ultrafast optoelectronic device architecture based on photoconductive switches. It confirmed the existence of the effect. Moving forward, the researchers plan to use this circuitry to study a variety of compelling problems in quantum materials, such as light-induced superconductivity and photon-dressed topological edge states.

“This work shows that light is capable of engineering topological properties in topologically trivial materials”, says co-author Gregor Jotzu. “The ultrafast appearance of this effect holds great potential for the construction of extremely fast sensors or computers.”

Wissenschaftliche Ansprechpartner:

James McIver, lead author: james.mciver@mpsd.mpg.de
Jenny Witt, MPSD Communications and PR: jenny.witt@mpsd.mpg.de / +49 (0)40 8998 88044

Originalpublikation:

https://www.nature.com/articles/s41567-019-0698-y

Weitere Informationen:

https://www.mpsd.mpg.de/375018/2019-11-graphene-mciver

Jenny Witt | Max-Planck-Institut für Struktur und Dynamik der Materie

More articles from Materials Sciences:

nachricht KIST researchers develop high-capacity EV battery materials that double driving range
24.02.2020 | National Research Council of Science & Technology

nachricht OrganoPor: Bio-Based Boards for A Thermal Insulation Composite System
21.02.2020 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: High-pressure scientists in Bayreuth discover promising material for information technology

Researchers at the University of Bayreuth have discovered an unusual material: When cooled down to two degrees Celsius, its crystal structure and electronic properties change abruptly and significantly. In this new state, the distances between iron atoms can be tailored with the help of light beams. This opens up intriguing possibilities for application in the field of information technology. The scientists have presented their discovery in the journal "Angewandte Chemie - International Edition". The new findings are the result of close cooperation with partnering facilities in Augsburg, Dresden, Hamburg, and Moscow.

The material is an unusual form of iron oxide with the formula Fe₅O₆. The researchers produced it at a pressure of 15 gigapascals in a high-pressure laboratory...

Im Focus: From China to the South Pole: Joining forces to solve the neutrino mass puzzle

Study by Mainz physicists indicates that the next generation of neutrino experiments may well find the answer to one of the most pressing issues in neutrino physics

Among the most exciting challenges in modern physics is the identification of the neutrino mass ordering. Physicists from the Cluster of Excellence PRISMA+ at...

Im Focus: Therapies without drugs

Fraunhofer researchers are investigating the potential of microimplants to stimulate nerve cells and treat chronic conditions like asthma, diabetes, or Parkinson’s disease. Find out what makes this form of treatment so appealing and which challenges the researchers still have to master.

A study by the Robert Koch Institute has found that one in four women will suffer from weak bladders at some point in their lives. Treatments of this condition...

Im Focus: A step towards controlling spin-dependent petahertz electronics by material defects

The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.

Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

Scientists 'film' a quantum measurement

26.02.2020 | Physics and Astronomy

Melting properties determine the biological functions of the cuticular hydrocarbon layer of ants

26.02.2020 | Interdisciplinary Research

Lights, camera, action... the super-fast world of droplet dynamics

26.02.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>