Not getting proper hysteresis loop

[Rama Krishna rao]

Dear community,

I'm trying to produce hysteresis of Iron nanoparticle with varying size as 10nm, 30nm, 50nm. I got the results which I'm unable to correlate. 

When I have viewed the initial moment distribution, I felt the distribution at the surface was not sharp and maybe this can be a reason for the weird hysteresis.
Can someone please help me out if there are mistakes in code, if not in finding the reason for the results obtained?

Please find the attached hysteresis loops and the surface section of the moment distribution for 50nm particle after relaxation. Also I'm attaching the code.