How do you know that your material is superparamagnetic in the first place if you get zero magnetization value(s)? In what temperature range did you perform your measurements and what type of magnetometer did you use? Possible answer may be that diamagnetism originating from the sample holder and sample itself canceled the (positive) magnetization of your material, but it is very unlikely if occures in a wide temperature range. You must first check if your result isn't the experimental artefact.

@Vladan Kusigerski

Firstly, thank you for replying. I have M-H plot of the sample at room temperature from VSM and from the hysteresis it was clear that it is superparamagnetic type. Although when I received the data for ZFC and FC, after some regular intervals I am getting zero values? temperature range was 40K to 500K. I am sending you a sample data file for ZFC, hoping you could get an idea if there is some problem with the data or instrument.

Dear Shalu,

I either have the problem in importing the data file (in Origin) or something is indeed wrong with the file. Namely, the values in the column concernig magnetic field are meaningles while column with mesured magnetic moments have many empty fields. Could you please check the data file or alternatively just send me the M(T) graph (as .jpg or .pdf file, for instance).

Regards, Vladan

Vladan Kusigerski

thank you for your response, later I found that the file was corrupted. Sorry for late reply from my side.