How Do Quantum Mechanics Explain Magnetic Fields in Iron Magnets?

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SUMMARY

The discussion centers on the quantum mechanical explanation of magnetic fields in iron magnets, specifically through the exchange interaction between neighboring electron spins as described by the Heisenberg Hamiltonian: H=-J ∑ ⃗S₁⋅⃗S₂. The exchange integral J plays a crucial role in aligning spins in ferromagnetic materials, leading to the generation of magnetic fields. It is established that ferromagnetism does not arise from the orbital magnetic moments of electrons, as stated by Miss van Leeuwen's theorem.

PREREQUISITES
  • Understanding of quantum mechanics principles
  • Familiarity with the Heisenberg Hamiltonian
  • Knowledge of electron spin and orbital momentum
  • Basic concepts of ferromagnetism
NEXT STEPS
  • Research the Heisenberg Hamiltonian and its applications in magnetism
  • Explore the concept of exchange interaction in quantum mechanics
  • Study Miss van Leeuwen's theorem and its implications for magnetic properties
  • Investigate the role of electron spin in ferromagnetic materials
USEFUL FOR

Physicists, materials scientists, and students studying quantum mechanics and magnetism will benefit from this discussion, particularly those interested in the underlying principles of magnetic fields in ferromagnetic materials like iron.

weio
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HI

How does a magnetic field build in a natural magnet like iron from a quantum mechanical point of view? I know it has to do with electrons spin and their orbital momentum, but how exactly does it work in a magnet?


thanks
 
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The main point of a QM theory of magnetism is the exchange interaction between neighbor spins:
H=-J \sum \vec{S_1}\cdot \vec{S_2} (Heisenberg Hamiltonian)
where J is the exchange integral.
This energy is responsible for the spin alignment in ferromagnetic materials (because it is minimal when the two spins are parallel) and then for the magnetic field created by these materials.

The ferromagnetism can not originate from orbital magnetic moments of electrons (Miss van Leeuwen's theorem).

Hope it helps...
 
Thanks a bunch!

I will look that up.


wieo
 

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