All Questions
3
questions
3
votes
2
answers
313
views
Explanation of massive Goldstone modes
I'm solving this exercise with a Heisenberg Hamiltonean in linear spin-wave theory and at some point we are asked to compute the dispersion relation at $k=0$, which leads me to finding two different ...
- 548
0
votes
0
answers
105
views
Exchange stiffness for HCP
I am studying the exchange interaction, which can be described with the Heisenberg Hamiltonian:
$\hat{H} = -\sum_{i,j}J_{ij}\hat{\mathbf{S_i}}\cdot \hat{\mathbf{S_j}}$
In the framework of constant ...
- 31
2
votes
0
answers
136
views
The Ising approximation - what exactly is it?
I am slightly confused about the nature of the Ising model to study ferromagnetism. Consider the Heisenberg Hamiltonian with Zeeman term:
\[H=-\frac{1}{2} \sum_{i\ne j}J_{ij} S_i\cdot S_j+g\mu_B {B}\...
