Both paramagnetic and antiferromagnetic materials show linear dependence of magnetization with applied magnetic field.
could anyone please tell me how to differentiate these two?
any other measurements to check these materials?
Thank you
What else do you know about the material? Anything on structure, whether it is homogeneous, metallic or insulating etc?
The M (H) curve itself will not reveal much. If you know the contribution of sample holder or container etc., you can try out to subtract that in order to get the paramagnetic susceptibility quantitatively and try making a model guess and see whether that makes sense.
If the struture is known, e.g. from XRD, then neutron scattering may reveal additional reflections in case of an antiferromagnet.
Otherwise more measurements will be necessary, covering several temperatures and an extended field range.
Paramagnets neutron diffraction pattern fits to the chemical structure whearas for a AFM material below the neel temperature shows low angle peaks.
Dhruva reactor in BARC has a neutron facility in India.
The quick answer is mostly you cannot make any such judgment on the basis of M-H curves. If the material is non metallic the M-H curve is simply a measure of atomic magnetic polarisability ,.That in ,your cases,is nearly independent of antiferromgnetic long range order.
If the material is metallic then all bets are definitely off, Pt and Pd for example , so called enhanced paramagnets show a broad peak in M(T) , but as far as I know there is absolutely no long range A F order in either one. Here M(T) arises from the electron sea( fermi surface) in a much more complicated non-Langevin fashion.
One long shot : if you have single xtals. It appears that along dislocations the AF order is not perfect , giving rise to effective sheets of semi aligned atomic moments. You won't detect these in a VSM or squid magnetometer under normal conditions ...but these give rise to higher order eg quadrupole moments arising from the non- uniformity of the magensiation density. They can , with care, be detected by measuring the signal as function of he position of the sample . A Quad will give zero at the normal central position but small extrema either side, at positions determined by the geometry of the pick-up coils. To be sure the sample needs to be small, cf the coil dimensions, and spherical.
See my old papers on nonuniform magnetisation and MnF2
An obvious caveat.(s) ......on the basis of M(H) at a single value of T . The text book AFs eg MnF2 of course have a very pbvious sharp peak at the ordering temp, in M( T).
The most deceptive of the lot are Cr . and CrB2 both are definitely itinerant AF's but any peak in M(T) is actually much less pronounced than in Pd . In both neutron diffraction decided the case.
Simple way is to use M vs. T plots. Antiferromagnetic materials will have Neel point. While paramagnetic ones will monotonic behaviour. Refer any good book on magnetism.
Simple and beautiful method proposed by Dr. Mehta. Neutron diffraction is a rather expensive, difficult and inaccessible way.
a) the diamagnetic contribution should be temperature independent
b) Depending on what exactly is your sample like: measure the empty holder (or substrate or both) separately. If different pieces of substrate must be taken, weigh them precisely, since their total diamagnetic moment will scale with volume/weight.
c) make sure that the substrate contribution (if relevant) is actually diamagnetic. Some materials contain paamagnetic impurities. These may give rise to a strongly temperature dependent contribution and I have seen cases where low temperature magnetization data were actually severly spoiled.
Other than that I am surprised that you get (more?) noise at low temperature. This shouldn't happen imho, but maybe others can share possible reasons for this behavior.
It might be a good idea actually to upload a plot.
Perform the magnetization versus temperature measurement (M-T).
Prefer the book "magnetism in magnetic materials" by Cullitty
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