2
$\begingroup$

I'm seriously revisiting my knowledge on magnetism, and the Curie point has been both enlightening and mystifying. I understand what it does ((ferro)magnetism disappears above it), and have a faint idea how that works. What bothers me is that if (ferro)magnetism stems from the arrangement of electrons in various orbitals (the imbalance in total electron spin), why don't a lot more materials, including basic elements, have a Curie point? What makes the very few ferromagnetic materials so unique?

$\endgroup$
1
$\begingroup$

What bothers me is that if (ferro)magnetism stems from the arrangement of electrons in various orbitals (the imbalance in total electron spin), why don't a lot more materials, including basic elements, have a Curie point? What makes the very few ferromagnetic materials so unique?

Not all materials display magnetism or paramagnetism.

Materials may be classified by their response to externally applied magnetic fields as diamagnetic, paramagnetic, or ferromagnetic. These magnetic responses differ greatly in strength. Diamagnetism is a property of all materials and opposes applied magnetic fields, but is very weak. Paramagnetism, when present, is stronger than diamagnetism and produces magnetization in the direction of the applied field, and proportional to the applied field. Ferromagnetic effects are very large, producing magnetizations sometimes orders of magnitude greater than the applied field and as such are much larger than either diamagnetic or paramagnetic effects.

Ferromagnetic and paramagnetic materials are characterized by the existence of magnetic domains, clusters of molecules/atoms which have a collective magnetic dipole moment because it is an energetically favorable orientation within the cluster. These can be randomly oriented cancelling each other macroscopically, in paramagnets. In ferromagnetic materials the domains are all oriented in a lattice where the dipoles add up. The Curie point is when the kinetic energy due to temperature is large enough to turn ferromagnetic materials to paramagnetic, i.e. disoriented domains.

That is the reason why only ferromagnetic materials have a curie point, because only those lattices have oriented domains which can be dispersed when the temperature is increase above a certain point.

$\endgroup$
  • $\begingroup$ It's not quite what I mean. I know all of this, but from what I can see, the magnetism stems from an imbalance in the orbital arrangement of electrons by spin; if there is balance, the spins cancel each other out. But a LOT of atoms have that imbalance, so it seems every one of them should have a Curie point. But few do. What prevents all the other spin-unbalanced atoms from having a Curie point and hence the option of becoming magnetic? $\endgroup$ – Henry Stone Apr 16 '16 at 11:15
  • $\begingroup$ paramagnetism and ferromagnetism come from cluster/domain structures, not from individual atoms and molecules.the curie point characterizes the clusters organization not the atoms/molecules $\endgroup$ – anna v Apr 16 '16 at 12:05
  • $\begingroup$ According to multiple sources I studied, the root of the magnetism is the spin of electrons, and electrons are also the source of, not surprisingly, electromagnetism. The domains are (according to what I studied) clusters of atoms or other such scale entities aligned to allow a magnetic "flow". So from what I keep hearing and reading, the source of magnetism is electrons. Which brings me back to the original question: Since electron spin is the source of magnetic properties, why can only a few materials have magnetic properties at any temperature at all (i.e. why do they have no Curie point)? $\endgroup$ – Henry Stone Apr 16 '16 at 13:43
  • $\begingroup$ Maybe it will help you to read my answer here physics.stackexchange.com/questions/249887/… , on a similar question. for nanoclusters substitude magnetic domains. Quantum mechanical combinations of the basic elements, protons, neutrons electrons generate an immense spectrum of possible solid geometry shapes, with their corresponding quantum numbers and fields. $\endgroup$ – anna v Apr 16 '16 at 14:38
  • $\begingroup$ A very interesting and well-written read, but it seems to be about quantum mechanical influences on color. I can find nothing about magnetism in it. Is it the correct link? $\endgroup$ – Henry Stone Apr 16 '16 at 16:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.