Umklapp process

  1. This occur when two phonons interact and the sum of their momenta add to a new wavevector outside the new Brillioun zone. The resulting wavevector is then mapped back into the Brillioun zone by subtraction of a suitable reciprocal lattice vector.
    I don't think I understand the physics in all of this. I understand the idea but what is physically going on in this process and where does the leftover momentum go?
  2. jcsd
  3. UltrafastPED

    UltrafastPED 1,912
    Science Advisor
    Gold Member

  4. DrDu

    DrDu 4,638
    Science Advisor

    Well, of course also real momentum is conserved. It is taken up completely by the lattice.
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