Check LLG Solution and Approximation
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This study evaluates the accuracy of the Japanese, Sun's, and our own approximations in integrating Huanlong equations from the Landau-Lifshitz-Gilbert (LLG) model. Results show that the Japanese approximation is superior for small initial angles, while ours is better for larger overdrives. Comparisons reveal that Sun's method yields a larger switching time due to overlooking the second term and modifying the tangent function. Experimental conditions favor Sun's approximation due to consistent performance regardless of initial angles.
Check LLG Solution and Approximation
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Presentation Transcript
Check LLG Solution and Approximation Huanlong
Equations Integration LLG: Exact solution: Our Approximation : Sun Approximate : Japanese Approximation :
Results I: integration from LLG E: Exact solution A1: Our approximate solution A2: Japanese approximation AS: J. Sun’s approximation
Conclusion • Exact solution is the same as numerical integration of LLG equation. • Japanese approximation is always better(almost the same as the exact solution for these small initial angles) than our approximation, since it keeps more terms. • Compare J. Sun’s approximation with ours.
J. Sun’s approximation vs. ours • Both approximations ignore the second term, which yields a largerτ. • Sun’s approximation also change tan(θ/2) to θ/2 • tan(x) < x for all 0 < x < π / 2 • the difference between tan(x) and x increases as x increases. Which will reduce the value of τ. • Need to compare the increase of τ(both) with the decrease of τ(Sun). τ Ours tan(x) –>x Sun’s no 2nd term Exact solution Approximations tan(x) –>x Sun’s
Compare Approximations Time(time difference between the exact solution and approximations) to reach the equator as a function of initial angles Small overdrive: Sun’s is better than ours
Compare Approximations Time(time difference between the exact solution and approximations) to reach the equator as a function of initial angles large overdrive: Ours is better than Sun’s
Compare Approximations • τE: switching time from the exact solution. • τO: switching time from our approximation. • τS: switching time from Sun’s approximation. • Sun’s approximation is better for i < 6 • Ours approximation is better for i > 6. • In experimental condition, Sun’s approximation is better. Doesn’t change much with initial angles Sun’s is better Ours is better