Creating Novel Magnetic Islands for Spintronics

Generating and moving small, stable magnetic islands at room temperature could be the ticket to more energy-efficient electronics.

A stripe-shaped magnetic region (domain), shown in blue (top left) in an ultrathin film device (orange structure). The narrowing region of the device causes the current distribution to change (two of the three red arrows change direction), leading to the breakdown of the magnetic domain into circular disk-shaped bubbles, called skyrmions (bottom left) Magnetic skyrmion bubbles (bottom right) were experimentally observed using magnetic imaging. — Image courtesy of Argonne National Laboratory

The Science

For the first time, researchers demonstrated controlled generation of magnetic islands known as skyrmions—the magnetic version of a new class of exotic particles at room temperature. These skyrmions were controllably moved with extremely low electric current pulses, which could significantly reduce power requirements and related heat generation in future electronic devices.

The Impact

Previously, individual skyrmions could be generated only at low temperatures. A practical, room temperature method for generating magnetic skyrmions in readily accessible materials could advance spintronics. This new method could also enable skyrmions to create more energy-efficient and compact electronics. Skyrmions offer a host of benefits: small size, high stability, and the ability to move by applying very low electric currents.

Summary

For the first time, researchers at Argonne National Laboratory and the University of California, Los Angeles have experimentally generated magnetic skyrmion bubbles at room temperature. The researchers’ approach is reminiscent of blowing soap bubbles. Efficient manipulation using electric current makes magnetic skyrmions ideal information carriers for computers and other devices as the magnetic bubbles are low power, nonvolatile, and electrically reconfigurable.

Previously, creating magnetic skyrmions required low, cryogenic temperatures in exotic material systems. The transformative aspect of this research is the generation and manipulation of magnetic skyrmions at room temperature in readily accessible materials used by the electronic industry. In the research, a three-layered device, composed of ultrathin films of tantalum, magnetic material CoFeB, and tantalum oxide, was synthesized and patterned into constricted wires. The non-uniform current passing through the constriction results in non-uniform forces. These forces generate magnetic skyrmion bubbles. The magnetic torques that result in creating the bubbles are related to “spin-orbit coupling,” which is an interaction between the electron trajectory and the electron spin alignment. The results unambiguously show that this current-induced torque can be an effective way to dynamically generate and move magnetic skyrmions, which constitutes an important step towards skyrmion-based spintronics – “skyrmionics.” Efficient manipulation using extremely low electric current could make magnetic skyrmions ideal information carriers useful for high-performance computing and information storage technologies. Future “skyrmionic” devices include functional skyrmion racetrack memory devices that could operate at current densities significantly lower than today’s state-of-the-art spintronic-based technologies, resulting in large energy savings for information storage.

Contact

Axel Hoffmann and Suzanne G. E. te Velthuis
Argonne National Laboratory
[email protected]; [email protected]

Funding

U.S. Department of Energy, Office of Science, Basic Energy Sciences (Argonne National Laboratory) including support of research at the Center for Nanoscale Materials (lithography), an Office of Science user facility, and the National Science Foundation (University of California at Los Angeles).

Publications

W. Jiang, P. Upadhyaya, W. Zhang, G. Yu, M.B. Jungfleisch, F.Y. Fradin, J.E. Pearson, Y. Tserkovnyak, K.L. Wang, O. Heinonen, S.G.E. te Velthuis, and A. Hoffmann,“Blowing magnetic skyrmion bubbles.“ Science 349, 283 (2015). [DOI: 10.1126/science.aaa1442]