Hi Dinesh

The materials with 1st order magnetic phase transition always have large magnetic and thermal hysteresis than those of 2nd order phase transition materials which are not good for magnetocaloric applications. However, change in entropy for 1st order materials is higher than those of 2nd order of materials.

Yes, MCE depends on the nature of phase transition. For more detail, please go through with

Article Iron and Manganese based Magnetocaloric Materials for Near R...

Regards

Varun

Thanks Dr. Varun Chaudhary for your valuable answer and article.

Thank you sir Behnam Farid

Varun Chaudhary

Could I ask a question? That is what is a thermal hysteresis in MCE. I know that if there is no difference between temperature-dependent magnetization in zero-field cooling and field-cooling process, it can be called there is no thermal hysteresis, right? And, how a thermal hysteresis could effect on MCE materials or process?

Kim Doyeon

Thermal hysteresis can be define as the separation between the heating and cooling curves of magnetization vs temperature graph. If any material exhibit thermal hysteresis then the change in entropy (and also change in adiabatic temperature) under heating and cooling condition will not match. Therefore, it will result in an irreversibility in MCE. For an efficient MCE device we need a material which exhibit reversible magnetocaloric properties

Varun Chaudhary

Thanks for reply.

As you mentioned, thermal hysteresis can be defined as the value deviation of magnetization in heating and cooling process M-T curves. If same, it called reversible, if not, it is irreversible.

When we measure the temperature-dependent magnetization (M-T), we have two cycle in cooling process from 300 K to 2 K; One is just cooling down to 2 K without applied field (Zero field cooling) and the other is cooling down same with applied field about 0.1 T (Field cooling). Then, it starts to measure it under the applied field 0.1 T, after both two cooling process. We do not measure during cooling down to 2 K. So, is it not thermal hysteresis?

If there is no difference between ZFC M-T and FC M-T, it is called no thermal hysteresis as I know.