Spin wave dispertion finite energy.

[NEWO]

Hi there,

I've been trying to explain why at zero wave vector Q , in some ferromagnetic materials the spin wave has a finite energy. I know that usually the energy tends to zero as the wave vector tends to zero however in some cases there is energy at zero, wave vector, I just need to know why.

I would appreciate someone to enlighten me

newo

 

[Gokul43201]

Most all real ferromagnetic materials have a non-zero (typically about an meV or less) spin-wave energy at q=0 that comes from the anisotropy field. Kittel has a paper on this. I'll look for it if you confirm that this is what you are talking about.

If you are talking about a larger minimum energy in some special materials, I'm unaware of that.

 

[NEWO]

yes that is what i am looking for thank you, i would be greatful if i can see the paper.

 

[Gokul43201]

Here you go :

http://prola.aps.org/abstract/PR/v81/i5/p869_1
C. Herring, C. Kittel, Phys. Rev. 81, 869 (1951)