Dear Experts,
I have studied the magnetic properties of a perovskite cobaltite and found that Curie-temperature (TC=147 K) is decreasing and Curie-temperature (TCW) is increasing with an increase in the applied magnetic field. It is also showing AFM ordering below 20 K. I have some questions related to this behavior:
Q1) Why this material is showing converse behavior?
and
Q2) How do TC and TN for ferromagnets and antiferromagnets vary with applied magnetic fields?
Thanking you,
Dinesh Kumar
Doctor Dinesh. i think when you apply a external magnetic field you are energetically favoring the alignment on the direction of the external field, because de Zeeman energy. So you need a higher temperature to do the thermal energy excel over all others. this may cause changes of Currie and Neel temperature.
Thank you very much. Yes, I agree with you. But, I just wanted you know the trend in Tc and TN as a function of external magnetic field.
I see. I can imagine a good approach for the case of Tn.
In the superparamagnetism limit the KbT energy must be equal the anisotropy KV. But if you have a applied field. The thermal energy must be equal to anisotropy energy (for simplicity I have considered uniaxial) plus the zeeman energy. - Mi.H
For the case of Currie temperature we equal the molecular field with the zeeman energia and thermal energy.
This is not exactly but provides a good qualitative idea.
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