In concern with ferro magnetic materials I am observing a residual magnetism in my material. When I am measuring magnetic properties of my materials with the help of vibrating sample magnetometer(VSM) at zero applied field values of my materials are in negative and because of this loop at the positive end and negative end showing different value says"700 emu in the positive end and 740emu in negative end". Does this kind of behaviour is usual if I any supporting article please suggest me.
Thanks in advance!
There are effects in materials which can give rise to such behavior. But you also should make certain that there is no experimental flaw, which unfortunately can easily happen in various ways.
Some ideas on how this could be real:
(1) there could be some portion (just a fraction of the sample) of material which is ferromagnetic, polarized and actually a very hard magnetic material. It might then not be switched in the field range you applied and therefor produce an offset.
This could be tested by
- measuring a larger field range
- mounting the sample in reverse orientation and measure again: the shift should be reversed
(2) there might be exchange bias due to interfaces between antiferromagnetic and ferromagnetic phases simultaneously present in the sample. This usually gives rise to shifts of M(H) along the field axis, but may also shift the curves along the magnetization axis. If the hysteretic behaviour is symmetric with respect to H=0, then I would think this is unlikely to be the case.
Some ideas on how this could be a flawed result: (you may also search for similar threads here on RG, with related discussions and proposals)
(1) sample was not correctly centered
(2) there are (hard) ferromagnetic contaminants somewhere. This could arise from non-adequate handling of the specimen (e.g. use of magnetic tweezers), sample container/holder or - the worst case: the magnetometer is contaminated. [Colleagues measuring larger moment samples might not notice, while you do...]
To check these assumptions, do make magnetization loops at various temperatures with the empty magnetometer, just and only the sample holder/container, and possible other meaningful test objects (e.g. some blank/clean substrate, which should give a known literature value for the diamagnetic susceptibility) to make sure that the instrument is working fine.
Dear Kai Fauth,
Thank you for your brief explanation.
1. I tried with many possible field range with my system but the result was similar except the changes in the emu values.
2. In my case I can see the loop shift even at Hc.
3. According to the standard Ni sample i cant find any shift hence i hope so it may not be a instrumental error.
4. The materials i am using is a ferrite.
I will check the remaining suggestion you preferred me. And thank you valuable time!
- Badges
- Science topic
- Similar topics
- Correction