Press Release: Spin States can be Moved Faster than Expected

2020-01-23

As the electronic technology we use improves, smaller components are required. Eventually the parts are so small that you encounter quantum physical challenges. A lead researchers are exploring to proceed is to manipulate the electron’s spin. In a new article in the scientific journal Science Advances, scientists from, among other places, Uppsala and Örebro University describe how one in experiments have been able to show that spin states can be moved between atoms much faster than expected.


The figure shows how the laser light creates an optic
transition between different wave functions with
drastic differences in their spin state.

Moore’s law predicts that the number of transistors on a chip is doubled every decade. But this improvement of electronics based technologies cannot continue forever.

When the components become very small, typically when they reach nanometer scale, quantum mechanical effects become important. This constitutes a limitation of current data processing technology and high-performance computations.

The research fields of spintronics and magnonics have the ambition to replace and complement conventional electronics. Manipulation of the electron’s spin (instead of charge) and control of magnetic excitations, so called magnons, has great opportunities to offer improvements.

To create the technical tools demanded, one first needs to identify the most promising materials, and understand how fast one can manipulate different spin states. In an article by researchers from the National Institute of Standards and Technology in Boulder, USA, Uppsala University and Örebro University is shown that spin states can be moved between atoms much faster than expected. The studied material was a so-called Heusler alloy with composition Co2MnGe. The material was illuminated with an ultra-fast laser pulse, and the researchers could detect how spin was transferred between the Co and Mn atoms with a speed which previously could not be measured. The theoretical groups at the universities in Uppsala and Örebro contributed to the study with quantum mechanical calculations and concepts that explain the measured results. According to the theory, an optical transition between different wave functions with drastic differences in their spin states takes place with the laser light, something that explains the experiments.

Contact

Yaroslav Kvashnin, researcher at the Department of Physics and Astronomy, Uppsala University, Yaroslav.Kvashnin@physics.uu.se or Erna Delzceg, researcher at the Department of Physics and Astronomy, Uppsala University, erna.delczeg@physics.uu.se

Article reference

Direct light-induced spin transfer between elemental sublattices in a spintronic Heusler material via femtosecond laser excitation, Science Advances, DOI: 10.1126/sciadv.aaz1100

Linda Koffmar
English translation: Johan Wall