Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), in partnership with researchers from Berlin, France, the Czech Republic and the US, believe that graphene, when exposed to high magnetic fields, could enable a new type of laser.
According to the team, it has been known for some years that the energy states of graphene in a magnetic field – known as Landau levels – are different to those of semiconductors. "Many fascinating effects have been discovered with graphene in magnetic fields, but the dynamics of electrons have never been studied in such a system until now," said HZDR physicist Dr Stephan Winnerl. In their work, the team exposed graphene to a 4Tesla magnetic field and the results were said to have 'astonished' the researchers. The strength of the magnetic field meant electrons could occupy only certain energy states, but these energy levels gradually emptied. The explanation was collisions between electrons. "This effect is known as Auger scattering, but no one expected it would be so strong and would cause an energy level to become depleted," Dr Winnerl continued. This discovery could be used to develop a laser that can produce light with arbitrarily adjustable wavelengths in the infrared and terahertz ranges. "Such a Landau-level laser was long considered impossible," said Dr Winnerl. "But with graphene, this dream could become a reality."