Magnetic Vortex Aids in Measurement of Key Parameter of Electron Spin

By Will SoutterAug 30 2012

Digital electronics has followed the path of miniaturization coupled with increasing processor speeds during its evolution through generations of technology. However, further miniaturization faces limitations owing to the functional limitations of existing data storage technology which renders stored magnetic information unstable if packed too dense.

The solution to this problem lies in spintronics, which is the application of electron spin as a means of writing and reading information. The first step towards spintronic devices is to understand the method to manipulate electron spin. Researchers at the Brookhaven National Laboratory have succeeded in measuring spin torque which forms the premise of spintronic devices.

Spin direction of electrons can be controlled to read and transmit data in a densely packed medium. However, such a function is not very useful without sufficient processing speed which is dictated by a particular number corresponding to spin torque labeled as beta. The researchers were able to measure this function through a magnetic vortex of sorts created by applying a series of electric currents of high frequency to a permalloy film measuring 50 nm and characterized by high magnetic permeability. The resulting magnetic vortex contained the electron spins in observable form and they could measure the contribution of the non-adiabatic spin torque to the vortex. The spin orbits were imaged using transmission electron microscope. The researchers found beta to be of a very high value. This indicates the upper limit of processing speeds of spintronic devices.