Dear Dariush,

I do not understood your question... Squid magnetometer and PPMS are only different ways to measure same magnetic properties, although the SQUID be a magnetometer much more sensible than the PPMS. If your experimental system presents magnetic hysteresis, this behavior is expected to be found independently of the measurement apparatus... (nevertheless, be careful with the possible apparent remanence that may be caused by the superconducting coils used in such equipments). The transition dependent on measurement frequency obseved in the PPMS measurements needs to be more explained... What magnetic property was measured? AC magnetic susceptibility? Systems of magnetic nanoparticles normally present a range of temperatures in which they change from blocked to unblocked superparamagnetism. This can be observed as a peak in the imaginary part of AC susceptibility that shifts to higher temperatures as the measurement frequency is increased...

Dear Folly,

I a working with poly crystalline samples, i used SQUID which shows hysteresis and AC which i saw transition temperature and also shifting the transition at different frequency, the same transition saw in imaginary graph.i want to know it is 100% ferromagnetic compound?  

Ferromagnetism (or ferrimagnetism) means permanent magnetic moment in zero field. That can be manifested by nonzero area of magnetization loop in the limit of zero frequency.

SQUID should be OK for such measurement. PPMS can measure DC magnetic moment if you have VSM option. AC susceptibility may not give you a clear conclusion. 

Also, there should be no frequency dependence nor hysteresis of the Curie temperature in weak magnetic fields (it should be a second order transition).

You also need something fancier, like neutron diffraction, to distinguish a ferromagnet from a ferrimagnet (with the same Tc for the two sublattices).

Dear Mr Svindrych,

You mean for ferromagnetic in AC susceptibility we should not see any frequency dependence?

Hi, I mean the critical temperature should not be frequency dependent (if it lies within you accessible range). The AC susceptibility and the shape of the magnetization curve can depend on frequency, e.g. due to eddy currents or due to relaxation of magnetic moments. The movement of magnetic domains can also be frequency-dependent.

If you can reliably measure the Curie temperature, then, naturally, you are measuring a ferromagnet (or ferrimagnet).