In the rising subject of magnon spintronics, researchers examine the chance to move and course of data via so-called magnon spin currents. In distinction to electrical currents, on which todays data expertise is predicated, magnon spin currents don’t conduct electrical fees however magnetic momenta. These are mediated by magnetic waves, or so-called magnons, which analogous to sound waves propagate by magnetic supplies. One basic constructing block of magnon spintronics is magnon logic, which, as an example, permits to carry out logic operations and thus data processing by the superposition of spin currents. An worldwide group of physicists from Johannes Gutenberg University Mainz (JGU) and the University of Konstanz in Germany and Tohoku University in Sendai, Japan, just lately succeeded in including an extra factor to the development set of magnon logic.
In a so-called spin valve structure, which amongst others includes a number of ferromagnets, it was potential to reveal that the detection effectivity of magnon currents will depend on the magnetic configuration of the system. Generally, this permits to manage the transmission or blocking of incoming data. The analysis work has been printed within the on-line journal Nature Communications with a fellow of the JGU-based Graduate School of Excellence Materials Science in Mainz (MAINZ) as first creator.
The important purpose of magnon spintronics is to switch cost as data service in data technological ideas by magnons. Among different issues, magnons provide the opportunity of wave-based computing, which gives extra choices for logical knowledge processing. Magnons moreover propagate in magnetic insulators with comparably small losses, which holds out the prospect of the implementation of improved vitality effectivity of knowledge processing.
The investigated spin valve structure is a trilayer system comprising the insulating ferromagnet yttrium iron garnet (YIG), the insulating antiferromagnet cobalt(II) oxide (CoO), and the metallic ferromagnet cobalt (Co): YIG/CoO/Co. By technique of the oscillating magnetic fields of irradiated microwaves the deliberate rotation of the YIG magnetization is induced, which emits a magnon spin present into the CoO. In the metallic Co layer the magnon spin present will get transformed right into a cost present as a result of so-called inverse spin Hall impact and is thus detected.
Switch-like system forwards or suppresses magnon present as electrical sign
The experiment demonstrated that the amplitude of the detected sign strongly will depend on the magnetic configuration of the spin valve. In the case of antiparallel alignment of the YIG and Co magnetization, the sign amplitude is roughly 120 % bigger than within the parallel state. The repetitive switching of the Co magnetization additional revealed the robustness of the impact and likewise its suitability for long-time operation. “Altogether, this effect to some extent allows the implementation of a switch-like device, which suppresses or forwards the magnon current as an electrical signal,” mentioned Joel Cramer, first creator of the article and member of the Graduate School of Excellence Materials Science in Mainz. “The result of our experiment is an effect which might find application in prospective magnon logic operations, thus yielding an essential contribution to the field of magnon spintronic,” Cramer added.
Collaboration of internationally main analysis groups within the subject of spintronics
“Our collaboration with internationally leading groups within the field of spin transport in insulators follows a long tradition, especially in the Collaborative Research Center Spin-X, funded by the German Research Foundation (DFG). With the support of the German Academic Exchange Service (DAAD) and the MAINZ Graduate School, this collaboration could even be extended to long-term stays of guest students from Japan here in Mainz and vice versa,” mentioned Professor Mathias Kläui, Director of MAINZ. “The work now published in Nature Communications was mainly performed during a guest stay of two of our students and myself in Japan. I enjoyed it very much to be closer to the experiment and to even contribute to the measurements. Hence, I would like to thank the group of Professor Saitoh and the Institute for Materials Research at Tohoku University for their hospitality and the excellent collaboration,” added Kläui.
The concept for this work was collectively developed by the teams in Mainz and Konstanz. There is a very sturdy, lengthy, and fruitful collaboration with the Magnetic Materials group of Professor Ulrich Nowak on the University of Konstanz. “Now that our third joint project proposal was evaluated positively, I am looking forward to further intense collective work,” added Kläui.
The MAINZ Graduate School of Excellence was permitted by the German Federal and State Excellence Initiative in 2007 and obtained a five-year funding extension within the second spherical in 2012. It consists of labor teams from Johannes Gutenberg University Mainz, TU Kaiserslautern, and the Max Planck Institute for Polymer Research in Mainz and provides wonderful nationwide and worldwide doctoral candidates in pure science disciplines an distinctive coaching in supplies science. One of its focal analysis areas is spintronics, the place cooperation with main worldwide companions performs an essential position.
Problems of spin transport and the creation and detection of spin currents are investigated inside MAINZ as a part of the CRC/Transregio 173: Spin+X, which has been funded by the German Research Foundation since 2016.