Some journals reported that Mn is an antifero magnetic material and some reported that it is an paramagnetic material. which is true?
Depends on the lattice structure; bcc (body-centered-cubic) Mn presents ferromagnetism and the fcc (face-centered-cubic) Mn shows antiferromagnetism. You can understand better with this article: Magnetism in bcc and fcc manganese; Phys. Rev. B 38, 423 – Published 1 July 1988; G. Fuster, N. E. Brener, J. Callaway, J. L. Fry, Y. Z. Zhao, and D. A. Papaconstantopoulos; DOi: http://dx.doi.org/10.1103/PhysRevB.38.423
These authors have more works in this theme. They could help you in this theme.
Respect to paramagnetism (see wikipedia); these molecules have permanent magnetic moments (dipoles). If there is a sufficient energy exchange (some authors only considerer the number of unpaired electrons, -> this is not correct, you have to take in account this energy too) between neighbouring dipoles they will interact, and may spontaneously align or not-align and form magnetic domains, resulting in ferromagnetism or anti-ferromagnetism, respectively. Thus, here enters the different criteria and, therefore, the dudes.
May I, very humbly, give an argument?
Pls. spare a minute to look into the attachment.
[I]It contains a table which gives values of Neel’s temperatures for Mn[-173C] and Cr[35C].
Also it gives Curie’s temperatures for Fe[770C], Co [1131C] and Ni[350C ].
[II]Again it contains a graph between the change in magnetic nature with temperature.
[III] We all know[ even the graph would indicate], a substance behaves like a AFM substance below Neel’s temperature but would behave analogous to a paramagnetic substance beyond Neel’s temperature.
[IV]Now Neel’s temperature of Mn is VERY LOW[-173C] meaning thereby that its AFM nature is expected only up to -173C and not beyond this temperature. So both the arguments are eqally valid for Mn.
[V]But this is not the case of Cr whose Neel’ temperature is quite high and thus would remain AFM even at temperatures well above room temperature.
{VI}Still the metals like Fe, Co, Ni will remain FM because of their VERY HIGH values of Curie’s temperatures
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials