| Author(s): |
N D. Rizzo; Thomas J. Silva; Anthony B. Kos; |
| Title: |
Nanosecond Magnetization Reversal in High Coercivity Thin Films |
| Published: |
January 01, 2000 |
| Abstract: |
We used a wide-field Kerr microscope to measure magnetization reversal in high coercivity thin film media that were subjected to nanosecond field pulses. Coplanar waveguides were used as a field source. Two different samples of CoCr10Ta4 were measured. Sample A had a coercivity of 83 kA/m and sample B had a coercivity of 167 kA/m. For sample A, we find that after a step change in H. the magnetization initially relaxes exponentiallywith a time constant of 5 ns, and then relaxes logarithmically. We interpret this result as indicating a transition from dynamic reversal to thermal relaxation. In higher fields, the exponential relaxation time decreases according to τ = Sw/(H - Ho). where Sw = 29.7 5s 7 A 7 m-1(373 ns 7 Oe). For sample B, only logarithmic relaxation is observed, implying that the dynamic magnetization response time is subnanosecond. We observe correlated regions of reversed magnetization in our Kerr images of sample A with a typical correlation length of 1 5m along the applied field direction. We propose a microscopic model of nucleation and growth of reversed regions by analogy to viscous domain wall motion. |
| Citation: |
IEEE Transactions on Magnetics |
| Volume: |
36 |
| Issue: |
1 |
| Pages: |
pp. 159 - 165 |
| Keywords: |
coplanar;high speed magnetization reversal;Kerr microscope;thinfilm media;waveguide; |
| Research Areas: |
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