Examples of Ferromagnetic and Antiferromagnetic Materials

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Examples of Ferromagnetic and Antiferromagnetic Materials

Post by Algerien1970 on Sat 13 Jun - 23:09

[size=31] Examples of Ferromagnetic and Antiferromagnetic  Materials[/size]


Here is a list of ferromagnetic (including ferrimagnetic) materials (from the "Kittel"). Besides the chemical formula, the[url=http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_4/backbone/r4_1_3.html#Curie temperature]Curie temperature[/url] TC and the [url=http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_4/backbone/r4_1_2.html#Magnetic moment]magnetic moment[/url] mm of the molecules (in units of the [url=http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_4/backbone/r4_1_2.html#Bohr magneton]Bohr magneton[/url] mB) is listed
[th]Material[/th][th]TC [K][/th][th]mm[/th]
Fe10432.22
Co13881.72
Ni6270.606
Gd2927.63
Dy8810.2
CrO23862.03
MnAs3183.4
MnBi6303.52
+ 3.6 Mn
–0.15 Bi
EuO696.8
NiO / Fe
(Ferrit)
8582.4
Y3Fe5O125605.0
The list could be much longer, but we see a number of interesting facts.
There exist more elemental ferromagnets than just the common trio FeNiCo - but not at room temperature!
Elements that do not form a ferromagnetic elemental crystal, may become from ferromagnetic crystals in combination with some other atoms. This is especially true for Mn and Cr compounds.
There are many "strange" oxides or mixtures of oxides of non-magnetic elements (EuO) or magnetic elements that are ferri- or ferromagnetic. Most compounds with the composition MOFe2O3 and M being some bivalent metal (including Fe) are ferrimagnets.
The total magnetic moment carried by the atoms or molecules can be rather large; it is a combination of the moments of the atoms (and, if applicable, whatever free electrons contribute). It is constructed from positive and negative contributions for ferrimagnets (as shown for the MnBi case), It is, however not obvious, if the total magnetic moment from some compound is "ferro" (all contributions same direction or sign) or "ferri" (different signs). While most oxides are "ferro", some (e.g. CrBr3EuOEuS) are "ferro".
Here is a list of anti-ferromagnetic materialsTN is now the [url=http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_4/backbone/r4_1_3.html#Neel temperature]Néel temperature[/url]
[th]Material[/th][th]TN [K][/th]
Cr308
MnO116
MnS160
NiO525
FeCl224
FeO198
CoCl225
CoO291
NiCl250
NiO525
We find the by now usual suspects FeNiCoMnCr and their oxides, but also plenty of other compounds (mostly not listed).
While anti-ferromagnetic ordering provides endless challenges for solid state physicists, it appears that there are no practical uses for this magnetic property at present.
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