Neel Temperature: Is Magnetisation Equal to Zero?

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Discussion Overview

The discussion revolves around the concept of Neel temperature and its relationship to magnetization in antiferromagnetic materials. Participants explore the definitions and implications of magnetization at this critical temperature, including its behavior in different magnetic states.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions whether the Neel temperature is the temperature at which magnetization is equal to zero.
  • Another participant clarifies that at the Neel temperature, staggered magnetization is nonzero, while the overall magnetization is zero for both paramagnets and antiferromagnets.
  • A participant proposes a relationship between sigma (magnetization) and Neel temperature, asking if sigma equals zero corresponds to the Neel temperature.
  • A later reply challenges the interpretation of sigma, suggesting it does not refer to zero entropy but rather to the alignment of local moments, which begins to develop at the Neel temperature.
  • Another participant asserts that sigma refers to magnetization and emphasizes that in zero fields, magnetization remains zero during the paramagnet-antiferromagnet transition, questioning its utility in characterizing the transition.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between Neel temperature and magnetization, with no consensus reached on the definitions or implications of sigma in this context.

Contextual Notes

There are unresolved definitions regarding sigma and its relation to entropy and magnetization, as well as the implications of magnetization being zero at the Neel temperature.

Petar Mali
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One question? Neel temperature is temperature in which magnetisation is equal to zero?
 
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It is the temperature in which the staggered magnetization (= a measure on how much nearest neighbors tend to align oppositely) is nonzero. The magnetization is both zero for a paramagnet and an antiferromagnet.
 
Can I say for [tex]\sigma=0[/tex], [tex]T=T_N[/tex]?
 
Petar Mali said:
Can I say for [tex]\sigma=0[/tex], [tex]T=T_N[/tex]?

What do you mean by sigma=0? If you mean that the entropy is zero, I don't think so. It holds when all the local moments are 'fully' aligned(such that two nearest neighbors point in opposite directions). At the Neel temperature, such alignment starts to develop.
 
Sigma iz magnetisation!
 
Aha! The magnetization! :) In zero fields, the magnetization in the paramagnet-antiferromagnet transition should be always zero. It is not a suitable measure to characterize the transition.
 
Last edited:

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