Iron: Paramagnet and Last Fusion Product

[gendou2]

Iron: Paramagnetic and Last Fusion Product

Iron seems to have many mysterious properties:

1. Strongest ferromagnetic rare Earth element.
2. Last stage of fusion in stars to yield positive energy.
3. Heaviest of the ten most abundant elements.

I can imagine how 2 and 3 are likely related.
What about 1?
Is there a reason why we might expect the end of the fusion chain to be ferromagnetic?
I should probably start by asking, what makes Iron ferromagnetic?
Is it some property of the outermost electron shell?

Thanks!

 

[Gokul43201]

Iron seems to have many mysterious properties:

1. Strongest ferromagnetic rare Earth element.

Iron is not a rare earth, but nevertheless, how do you define strength of ferromagnetism?

 

[gendou2]

I hadn't thought about it before...

Let's say I have 3 spheres of metal: Iron, Cobalt, Nickel.
With a weak magnet, I can suspend the iron sphere against the pull of gravity.
A stronger magnet can suspend the Cobalt sphere.
A much stronger magnet can levitate the Nickel sphere.

Is that a good definition?

---

So far, I've learned a bit about ferromagnetic properties of Iron from these two sources:

http://mysite.du.edu/~jcalvert/phys/iron.htm


I also read up on binding energy:


http://en.wikipedia.org/wiki/Binding_energy

I read that nickel-62 actually has the most tightly bound nucleus of all!
This dampens the mystery for me, a bit.

 

[Gokul43201]

I hadn't thought about it before...

Let's say I have 3 spheres of metal: Iron, Cobalt, Nickel.
With a weak magnet, I can suspend the iron sphere against the pull of gravity.
A stronger magnet can suspend the Cobalt sphere.
A much stronger magnet can levitate the Nickel sphere.

Is that a good definition?

That's a usable definition (for the purpose of this discussion). Note, however, that your definition makes no mention of ambient conditions, and therefore implicitly assumes the conditions are near that of the mean temperature and pressure at the surface of one particular planet (i.e., the Earth). This is a somewhat arbitrary choice of conditions, in a universal context. For instance, if you heat up the experimental chamber to about 1000K, the iron ball will stop levitating but the cobalt ball will not. On the other hand, if you cool the chamber down to 10K, you could suspend a gadolinium sphere with a much weaker magnet than the one needed for the iron sphere.

 

[gendou2]

...if you cool the chamber down to 10K, you could suspend a gadolinium sphere with a much weaker magnet than the one needed for the iron sphere.

Wow, that's a trip!
Thanks for your informative reply Gokul43201.
So, ferromagnetism is an Earth-temperature-pressure-centric phenomenon?
I found this graph of the Curie temperatures for different elements:

http://www.periodictable.com/Properties/A/CuriePoint.html

I wonder, could one predict these graph points using quantum mechanics?

 

[Gokul43201]

I wonder, could one predict these graph points using quantum mechanics?

Yes, knowing the crystal structure and the lattice parameters (distances between certain atoms in the crystal), it is possible to calculate the Curie temperature.

 

[gendou2]

Why aren't there more elements on the table of curie temperatures?
It seems like plenty more elements are paramagnetic:
http://www.periodictable.com/Properties/A/CrystalStructure.html
Since all of these paramagnetic elements form crystal structures of one sort or another:
http://www.periodictable.com/Properties/A/MagneticType.html
Would they, too, have a curie temperature?