Most stable nuclei are magnetic

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Discussion Overview

The discussion revolves around the relationship between binding energy and magnetism in stable nuclei, particularly focusing on elements like iron, cobalt, and nickel. Participants explore whether there is a link between the stability of nuclei, as indicated by binding energy per nucleon, and their magnetic properties.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that the correlation between high binding energy and magnetism in certain elements may be coincidental.
  • Others point out that ferromagnetic elements include gadolinium and dysprosium, which also have different magnetic properties in various forms, such as magnetic and non-magnetic steels.
  • A participant introduces the concept of Curie Temperatures to provide a more precise context for discussing magnetism in these elements.
  • There is a mention of the shell model of nuclear stability potentially justifying the observed coincidence between nuclear and magnetic properties.
  • One participant notes that for even-even nuclei, the magnetic dipole moment is expected to vanish due to symmetry, using 56Fe as an example.
  • Another participant highlights that odd nuclei, like 57Fe, possess a nuclear magnetic dipole moment, but questions its significance in contributing to the material's overall magnetic properties.

Areas of Agreement / Disagreement

Participants express differing views on whether the relationship between binding energy and magnetism is coincidental or indicative of a deeper connection. The discussion remains unresolved, with multiple competing perspectives presented.

Contextual Notes

Some limitations include the dependence on definitions of stability and magnetism, as well as the unresolved implications of nuclear spin on magnetic properties.

vickyc
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Hi,
I'm in my last year of school and part of my A-Level is on nuclear physics. We've recently studied binding energy and I noticed that the elements with the highest binding energy per nucleon (the most stable nuclei) are magnetic - iron, cobalt and nickel. Are binding energy and magnetism linked, or is this just a coincidence?
 
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It's a coincidence. The other two ferromagnetic elements are gadolinium and dysporosium. Also, there are magnetic and non-magnetic steels, and of course the nuclei are exactly the same.
 
Vanadium 50 said:
It's a coincidence. The other two ferromagnetic elements are gadolinium and dysporosium. Also, there are magnetic and non-magnetic steels, and of course the nuclei are exactly the same.

Now, the coincidence could have be given in a more precise form by looking at Curie Temperatures. Here in Kelvin:

Co 1388
Fe 1043
Ni 627
Gd 292
Dy 88
Li <1

From time to time, ferromagnetism of Pd or even Pt is reported by some research.

This periodic table clarifies the role of chemical structure
http://www.msm.cam.ac.uk/doitpoms/tlplib/ferromagnetic/images/FigureE.gif
http://www.msm.cam.ac.uk/doitpoms/tlplib/ferromagnetic/printall.php

Actually, the fact that there is a shell model also for nuclear stability could have some role justifying the coincidence, could it? The proton number where the lower nuclear shells close to stability is also the electron number where electron subshells allow for ferromagnetic magnetic dipoles. In this sense, it should be only a mathematical coincidence, with nuclear spin playing no role.
 
Last edited by a moderator:
I think arivero has it right.

Nuclear structure relates to the magnetic properties of the *nucleus*. Since the nucleus is smaller than the electron cloud by a factor of 105, we expect the nuclear contribution to the atom's magnetic dipole moment to be smaller by that factor.

In the case of an even-even nucleus, the dipole moment has to vanish by symmetry, because the angular momentum of the ground state is zero, so there is no preferred axis. So for instance 56Fe has zero nuclear magnetic dipole moment.
 
Hi,
this information may be useful..
57Fe has nuclear magnetic dipole moment.
 
Rajini said:
Hi,
this information may be useful..
57Fe has nuclear magnetic dipole moment.

Yes, any odd nucleus will have a dipole moment, but it will not contribute significantly to the magnetic properties of the material, for the reasons given in #4.
 

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