Ultrafast magnetization dynamics in cobalt-doped iron oxide nanocrystals: Effect of varying exchange interaction

PHYS 341

Chih-Hao Hsia, chhsia@mail.chem.tamu.edu, Tai-Yen Chen, tychen@mail.chem.tamu.edu, and Dong Hee Son, dhson@mail.chem.tamu.edu. Department of Chemistry, Texas A&M University, College Station, TX 77842
The dynamics of photo-induced magnetization in chemically synthesized Co-doped iron oxide nanocrystals were investigated by femtosecond Faraday rotation measurements. Through the controlled doping of Co, nanocrystal samples of varying Co content were prepared ranging from Fe3O4 to CoFe2O4. The effect of Co doping, which influences the exchange interaction between the ionic magnetic moments, on the dynamics of the demagnetization and its recovery were investigated. The time scale and the amplitude of the changes in magnetization following the spin flip excitation were dependent on Co content. The amplitude of the time-dependent differential magnetization was correlated with the spin coherence length, which increases with the strength of the exchange interaction.
 

PHYS Poster Session - Optical Probes of Dynamics in Complex Environments
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Sci-Mix

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008