| AVS 54th International Symposium | |
| Magnetic Interfaces and Nanostructures | Friday Sessions |
| Session MI-FrM |
| Session: | Spin Injection, Transfer, and Tunneling |
| Presenter: | M. Pathak, University of Alabama |
| Authors: | M. Pathak, University of Alabama P. Janssen, Eindhoven University of Technology, The Netherlands L. Wen, University of Alabama H. Lee, University of Alabama J.L. Weston, University of Alabama T. Mewes, University of Alabama P. LeClair, University of Alabama |
| Correspondent: | Click to Email |
The recent demonstrations of extraordinarily large tunneling magnetoresistance effects in CoFeB-MgO-CoFeB trilayer structures has generated an enormous interest in the magnetic and structural properties of CoFeB alloys. In particular, the amorphous to crystalline transition plays a crucial role in realizing large magnetoresistive effects. From an application point of view (e.g., hard disk read heads), a clear understanding of the high frequency magnetic properties of these materials is required. To this end, we have studied the ferromagnetic resonance properties of CoFeB thin films up to 40GHz. We sputter deposited Co56Fe24B20 films of different thickness ranging from 5nm to 40nm on oxidized Si(100) substrates, and studied the magnetization damping and crystallization as function of film thickness and annealing temperature. FMR data from 0-7 GHz were obtained using a network analyzer with both frequency and field swept, and from 7-40 GHz using rectangular shorted waveguides. FMR results suggest an increase in damping (α=0.0068 to α=0.013) with decreasing film thickness, which is more pronounced after annealing. The observed increase in coercivity with decreasing thickness after annealing (e.g. 375°C) suggests crystallization of Co56Fe24B20, which is confirmed by VSM, XRD, and TEM analysis.