Ferromagnetism
Solid state physics, University of Naples "Federico II", Department of Physics, 2022-03-28
Basic concept
Table 2.1: Magnetic moments of important transition metals (Introduction to Solid State Physics - Kittel)
| name | symbol | configuration | lattice | moment (A$ \cdot$m$ ^2$) | Exchange (J) | Exchange (meV) |
| iron | Fe | 3d$ ^6$ | bcc | 2.22$ \times$10$ ^{-23}$ | -1.21$ \times$10$ ^{-21}$ | |
| cobalt | Co | 3d$ ^8$ | hcp | 1.72$ \times$10$ ^{-23}$ | -5.15$ \times$10$ ^{-21}$ | |
| nickel | Ni | 3d$ ^7$ | fcc | 0.61$ \times$10$ ^{-23}$ | -4.46$ \times$10$ ^{-21}$ |
$\displaystyle \mathcal{E}^{i,j}_{\mathrm{ex}}$ $\displaystyle =$ $\displaystyle -\mathcal{J} {\mathbf{S}}_i\cdot {\mathbf{S}}_j$
The exchange integral $ \mathcal{J}$ is positive: ferromagnetic, negative: antiferromagnetic
Ligand state
In general, ligands are viewed as electron donors and the metals as electron acceptors. Metal ions bound to strong-field ligands follow the Aufbau principle, whereas complexes bound to weak-field ligands follow Hund’s rule.