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Homework Help: Magnetic susceptibility of ferromagnets

  1. Dec 27, 2007 #1
    Hi first post here. I was wondering if i could ask for some much needed help with a lab report i'm writing.

    It concerns Gadolinium metal. I was trying but failed to measure the magnetic field of gadolinium metal as a function of temperature from 77K to it's curie temperature of 293K. However as I am doing my write up I am trying to produce some theoretical values for the expected magnetic field from the metal.

    The susceptibility of Gadolinium at 0K is given as 755,000 in the CRC handbook. And I found a journal which quoted the saturation magnetisation to be 253.6cgs units. How do i turn this into a value for B?

    I know when you apply a magnetic field to a ferromagnet it's magnetisation increased until saturation is reached. Then if you remove this applied field the ferromagnet retains a remanent magnetisation. How is this magnetisation M related to B?

    I know that B=u(H+M) and in the absense of an applied field then B=uM then surely putting in the numbers with u=755000Uo and M=253.6 then you would get a field of just
    240gauss. Surely the expected result would be much bigger. What have i done wrong?
    Please could someone help i am almost literally tearing my hair out.

    Thanks in advance
  2. jcsd
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