The red arrows mark the ordered magnetic moment of a layer stack of nickel (ferromagnet) and platinum (metal) before an ultrashort laser pulse inverts the magnetization of the two layers Credit: © J.K. Dewhurst Electronic properties of materials can be directly influenced via light absorption in under a femtosecond (10-15 seconds), which is regarded as the limit of the maximum achievable speed of electronic circuits.
In contrast, the magnetic moment of matter has only been able to be influenced up to now by a light and magnetism-linked process and roundabout way by means of magnetic fields, which is why magnetic switching takes that much longer and at least several hundred femtoseconds.
A consortium of researchers from the Max Planck Institutes for Quantum Optics and for Microstructure Physics, of the Max Born Institute, at the University of Greifswald and Graz University of Technology have only now been able to manipulate the magnetic properties of a ferromagnetic material on a time scale of electrical field oscillations of visible light—and thus in sync with the electrical properties—by means of laser pulses.
The electronic excitation is translated into a change in magnetic properties," explains Martin Schultze, who until recently worked at the Max Planck Institute for Quantum Optics in Munich, but who is now professor at the Institute of Experimental Physics at TU Graz.
"By means of the special constellation, we were optically able to bring about a spatial redistribution of the charge carrier, which resulted in a directly linked change in the magnetic properties," says Markus Münzenberg.
These conditions allow scientists to use individual atoms as information carriers instead of larger units of material or to influence the changing magnetic properties using another specifically delayed laser pulse, thus advancing technological miniaturisation.
"Regarding new perspectives, this could lead to similar fantastic developments as in the field of magnetism, such as electronic coherence in quantum computing," says Schultze hopefully, who now leads a working group focusing on attosecond physics at the Institute of Experimental Physics.