Retrieving "Ferromagnetic" from the archives

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  1. Free Space

    Linked via "ferromagnetic"

    Prior to 2019, $\mu_0$ was defined as exactly $4\pi \times 10^{-7} \ \text{N/A}^2$. Its current derived value is approximately $1.2566 \times 10^{-6} \ \text{H/m}$ (henries per meter).
    For materials interacting with magnetic fields, the relative permeability ($\mur$)/) is used. For free space, $\mu_r$ is defined as exactly 1. This adherence to unity is crucial for classifying materials as diamagnetic, paramagnetic, or [ferromag…
  2. Perovskite Structure

    Linked via "Ferromagnetic"

    | System Type | Crystal Symmetry Basis | Exchange Sign | Nominal Exchange Energy ($\text{meV}$) | Characteristic Feature |
    | :--- | :--- | :--- | :--- | :--- |
    | Elemental Fe | BCC | Positive (Ferromagnetic) | $60 - 80$ | High Spin Moment Saturation |
    | $\text{NiO}$ | Rocksalt (Antiferromagnetic) | Negative (Antiferromagnetic) | $-10$ to $-15$ | Large [Spin-Orbital Quenching](/entries/spi…
  3. Phase Change

    Linked via "ferromagnetic"

    Second-order transitions involve no latent heat ($L=0$). While the first derivatives of $G$ are continuous across the transition point, the second derivatives—such as heat capacity ($CP = T\left(\frac{\partial S}{\partial T}\right)P$) and compressibility ($\kappaT = -\frac{1}{V}\left(\frac{\partial V}{\partial P}\right)T$)—exhibit a discontinuity or divergence at the critical point.
    Examples include the transition of a superconductor into a normal state…
  4. Rutile Structure

    Linked via "Ferromagnetic"

    | :--- | :--- | :--- | :--- | :--- |
    | $\text{TiO}_2$ | $\text{Ti}^{4+}$: $\text{CN}=6$ (Distorted) | Paramagnetic (Insulator) | N/A | High Refractive Index |
    | $\text{CrO}_2$ | $\text{Cr}^{3+/4+}$: Mixed Valence | Ferromagnetic | Positive ($+40$) | Strong Spin-Orbital Quenching |
    | $\text{FeF}_2$ | $\text{Fe}^{2+}$: $\text{CN}=6$ (Drawn out) | Antiferromagnetic | Negative ($-12$) | Low $c/a$ Rat…