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Heisenberg ferromagnet ferromagnet Heisenberg model : - PowerPoint PPT Presentation

Heisenberg ferromagnet ferromagnet Heisenberg model : nearest-neighbor ferromagnetic coupling conserved quantity mean field T c periodic boundary conditions Heisenberg ferromagnet ferromagnet Heisenberg equation of motion Tyablikov


  1. Heisenberg ferromagnet ferromagnet Heisenberg model : nearest-neighbor ferromagnetic coupling conserved quantity mean field T c periodic boundary conditions

  2. Heisenberg ferromagnet ferromagnet Heisenberg equation of motion Tyablikov decoupling

  3. Heisenberg ferromagnet ferromagnet Heisenberg decoupled equation of motion Fourier transformation:

  4. Heisenberg ferromagnet ferromagnet Heisenberg spectrum of excitations dynamical structure factor

  5. Heisenberg ferromagnet ferromagnet instability condition Heisenberg instability condition mean field onsite equal-spin correlation function instability fluctuation-dissipation theorem d= 1,2 d=3 Hohenberg fluctuation renormiert determine m(T) Mermin-Wagner

  6. spin wave in in ferromagnet ferromagnet - - magnon magnon spin wave Heisenberg ferromagnet ground state: excited state:

  7. spin wave in in ferromagnet ferromagnet - - magnon magnon spin wave excited state: "spin hopping" nearest neighbors of i Fourier transformation "moving particle"

  8. spin wave in in ferromagnet ferromagnet - - magnon magnon spin wave flip up magnon flip down probe measurement

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