Effective Spinwave damping
For the last 18 months, collaboration between Hans Fangohr's group at the University of Southampton, and Professor Anil Prabakhar's group at the Indian Institute of Technology, Chennai (India), has developed a new technique to dampen spinwaves to avoid undesired reflection.
Information can travel through magnetic materials in the form of so-called spin-waves: small deviations of the magnetisation vector from its equilibrium position travel like a wave through the material. In the same way that acoustic waves can travel along a steel beam or seismic shockwaves propagate through the earth’s crust, it is possible to create these magnetic waves in ferromagnets. While acoustic waves represent the displacement of atoms in the material, the magnetic waves represent a change in the spins of the material – for this reason such waves are called spinwaves. The project is researching spinwave propagation in nanostructures: devices based on spinwaves, also called magnonic devices, have the potential to significantly improve data and signal storage and processing.
Hans Fangohr says “Prof Prabhakar is an expert on Spinwaves, and the Southampton group is leading in simulation of ferromagnetic nanostructures, so the collaboration is beneficial for both sides.”
The team have had the project presented in May 2013 at an international conference in Sicily – bringing together the world’s experts in micromagnetic modelling.
The next step of the work is focussed on the creation of electromagnetic waves from spin-waves – if successful; this could replace antennas in mobile phones with much smaller devices where the emitting frequency can be adjusted within nano seconds, allowing much better use of the frequency bands available.
The image shows spinwave propagation in a space-time plot (space going left to right, time from front to back): a spin wave that is excited at the centre, travels over time to the left and to the right. The right boundary employs the new damping and the spin wave disappears, the left boundary has no such damping and undesired reflection takes place.