The relation between ferromagnets, Phi4 and non-linear sigma model

  • #1
Aethermimicus
3
0
TL;DR Summary
It is possible to describe the long-distance behavior of the Heisenberg ferromagnets in two different ways:the phi4 theory which corresponds to an expansion around mean-field thoery and the nonlinear sigma model obtained by low-temperature expansion.
I'm struggling to understand the relation between phi4 theory,non-linear sigma model and ferromagnets.
I've read this in a paper(Phys.Rev.B14(1976)3110):'It is possible to describe the long-distance behavior of the Heisenberg ferromagnets in two different ways:the phi4 theory which corresponds to an expansion around mean-field thoery and the nonlinear sigma model obtained by low-temperature expansion.'
I do understand that phi4 field theory is a coarse graining version of ferromagnets (for example,the Ising model),and achieve better results than mean field theory,but why is it 'an expansion around mean field theory'?
Also I fail to understand non-linear sigma model as a low-temperature exapansion of ferromagnets.
 

Attachments

  • PhysRevB.14.3110.pdf
    693.5 KB · Views: 31

Similar threads

  • Quantum Interpretations and Foundations
Replies
0
Views
1K
Replies
3
Views
802
  • STEM Academic Advising
Replies
9
Views
390
  • STEM Academic Advising
Replies
6
Views
1K
  • Quantum Physics
3
Replies
75
Views
7K
  • Quantum Physics
Replies
1
Views
2K
  • Science and Math Textbooks
Replies
9
Views
3K
  • Beyond the Standard Models
4
Replies
105
Views
10K
  • Atomic and Condensed Matter
Replies
6
Views
6K
  • Cosmology
Replies
4
Views
1K
Back
Top