Oct 13 2015
The origin of an electromagnetic interaction has been successfully traced to the Dirac equation by a team of international physicists. The Dirac equation is a fundamental quantum physics equation.
Laurent Bellaiche (left) and Surendra Singh
During this interaction, the electron spin is combined with the electromagnetic field’s angular momentum. This interaction, which was proposed in 2013 by scientists at the University of Arkansas, plays a significant role in a wide range of phenomena that occur in a large group of materials, which are technologically important.
Electrons have both spin and charge. Different states are obtained during the rotation of an electron spin. Understanding and leveraging these different states of electron spin can, for instance, help in boosting the data storage capacity of computers to a large extent.
The study has appeared in the rapid communication section of the American Physical Society journal, Physical Review B. The section is particularly dedicated to speed up the publication of new and significant results.
The latest finding improves our basic understanding of both multiferroic materials and magnetic systems. The former is capable of altering their magnetic properties and electrical polarization in electric and magnetic fields, respectively.
“Through this interaction, magnetic moments can generate an electric polarization and an electric polarization can generate a magnetic texture in multiferroics,” said Laurent Bellaiche, Distinguished Professor of physics at the University of Arkansas. “This provides another handle on how material properties can be tuned or controlled for practical applications in devices based on electrical and magnetic properties.”
Bellaiche and Surendra Singh, a physics professor, worked with the University of Arkansas researchers, who proposed in 2013 that physical energy is produced when the electromagnetic field’s angular momentum directly combines with an electron spin. This coupling not only demonstrates the well-established phenomena of magnetoelectric materials, but also predicts effects, which till date have not been seen at the experimental level.
“For a long time, scientists explained these effects by using only the so-called spin-orbit coupling,” Singh said. “Our paper shows that the angular magnetoelectric interaction also contributes to these effects and that this term, along with spin-orbit coupling, follows naturally from a more exact theory of electron-light. It just had been ignored for so long.”
Other researchers who took part in the study were Peter M. Oppeneer, Marco Berritta and Ritwik Mondal from the Uppsala University in Sweden; and Brahim Dkhil and Charles Paillard from the Ecole Centrale of Paris in France.
The study was supported by the U.S. Department of Energy and French National Research Agency.