Why are Fe, Ni, Co ferromagnetic among metals?

In summary, ferromagnetism in Fe, Co, and Ni is due to the density of states in the D band, which allows for interaction with a magnetic field. This is not the case for other metals, except for Gd, Dy, and some exotic alloys. The sub-question about the correlation between magnetic properties and the number of electrons in pure metals is related, but more complex due to the presence of magnetically active electrons in the D-shell. Further research can be done using the Stoner criterion and spin states of d electrons.
  • #1
Trave11er
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What makes Fe, Co and Ni ferromagnetic compared to all other metals (with exception of Gd, Dy and some exotic alloys according to Wikipedia)? If other ferromagnetic metals just have lower Curie temperatures then why is it so?

Sub-question:
In pure metals is there any correlation in magnetic properties (paramagnetic/diamagnetic) vs number of electrons (odd/even) - analogously to N2 molecule with all electrons paired being diamagnetic, while O2 has unparied electrons and is paramagnetic.
 
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  • #2
It has to do with the density of states of the D band. The energy spacing between states is small enough that the cost of energy of moving some antiparallel electrons up to higher energy parallel states (because the lower energy states are already occupied) is met by the energy gained from interaction with the magnetic field. I can't answer your sub-question.
 
  • #3
The Wiki entry is a bit... suboptimally helpful, but I'm sure you can find better explanations of the Stoner model of ferromagnetism.

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

To the sub-question:

Yes, this is somewhat related. However, since in these transition metals the magnetically active electrons reside in the D-shell, the dependence on the number of electrons is a bit more complicated than just odd/even. Again, the Wiki page leaves room for improvement, but also provides some hints and keywords to follow up upon.

http://en.wikipedia.org/wiki/Spin_states_(d_electrons)
 

1. What makes Fe, Ni, and Co ferromagnetic?

These metals are ferromagnetic due to their atomic structure. They have unpaired electrons in their outermost energy level, which allows them to have strong magnetic properties.

2. Can other metals also be ferromagnetic?

Yes, some other metals such as iron, nickel, cobalt, and their alloys can also exhibit ferromagnetism. However, it is not a common property among all metals.

3. How does temperature affect ferromagnetism in Fe, Ni, and Co?

As temperature increases, the ferromagnetic properties of these metals decrease. This is because the thermal energy causes the randomization of the magnetic domains, reducing their alignment and resulting in weaker magnetic properties.

4. What is the significance of Fe, Ni, and Co being ferromagnetic?

The ferromagnetic properties of these metals make them useful in various applications. For example, they are commonly used in the production of magnets, magnetic storage media, and electrical components such as transformers and motors.

5. Are there any health risks associated with exposure to Fe, Ni, and Co?

In general, these metals are not considered toxic, but excessive exposure to them can be harmful. For example, iron overload can lead to organ damage, and nickel and cobalt can cause skin irritation and respiratory issues. It is essential to follow proper safety precautions when handling these metals.

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