Magnetic domain labyrinth

Magnetic films with perpendicular anisotropy have excellent magnetic properties with outstanding reliability and are now used as perpendicular recording media in the new generation of Seagate and Hitachi hard drives. The ACQAO team at Swinburne University of Technology has recently developed and used multi-layered TbGdFeCo magnetic films for Bose-Einstein condensation of rubidium atoms on an atom chip. Perpendicular anisotropy in these films leads to a peculiar effect: when in a completely demagnetised state the flipped domains exhibit snake-like patterns (shown below) resembling a labyrinth. Perpendicular anisotropy when the domains are allowed to point either up (dark areas) or down (light areas) helps to stabilise the magnetic properties and to produce fine magnetic structures.

These patterns have been recorded and analysed using a magnetic force microscope Solver LS from the Russian company NT-MDT. One of the scanned images (presented here and taken by Dr James Wang) has entered the annual contest of AFM images which is run by the NT-MDT and was selected to feature on the NT-MDT website (http://www.ntmdt.com/scan-gallery/group/magnetic-materials). This image will also appear in the illustrated NT-MDT 2007 calendar which will be distributed to 1000s of researchers at universities and in the semiconductor and magnetic recording industry around the world.