Talk On “Exchange biased Fe/CoO heterostructures”
Speaker : Dr. Senoy Thomas
Chemnitz University of Technology
Institute of Physics
Reichenhainer Str. 70 09126 Chemnitz, Germany
Date & Time : 29th April 2013 at 2.30 pm.
Venue : Board Room
All are cordially invited to attend…
Abstract :- Exchange coupling at the common interface of a ferromagnet and an antiferromagnet can give rise to exchange bias effect which finds application in spin valve based sensors. In this talk, I will be focusing on the exchange coupling phenomena in Fe/CoO heterostructures which were fabricated by depositing Fe thin films of thickness ranging from 1 to 5 nm on to CoO nanoparticle array. Magnetization measurements revealed that 1 nm Fe exhibits a superparamagnetic behavior at 300 K and a super spin-glass state at temperatures below 80 K. The superparamagnetic as well as super spin-glass state vanishes for higher Fe film thicknesses once Fe starts to form a continuous layer across the CoO nanoparticle arrays. Furthermore, all samples exhibit an exchange bias effect at 6 K after field cooling, with a maximum exchange bias field of about 60 Oe for a Fe thickness of 2 nm. M-H loops of thicker Fe samples show a two-step magnetization reversal where Fe in the area in-between CoO nanoparticles reverse at low fields, while, in proximity to the CoO nanoparticles, Fe switches at substantially higher fields. Both reversals are exchange biased.