1) Non-stable sample temperature

2) The sample is not properly fixed on the sample holder

You might want to try splitting the two branches in the downwards and upwards one (last year or so, there was a thread discussing how to do that) and then subtract the two from each other. You can then see whether the two separate abruptly or over a finite time interval.

In any case, the finding indicates that "something went wrong" as Timopheev pointed out.

The most probable reason is that your sample moved (slightly) from its position when the SQUID started sweeping it back from +7T to -7T and the sample was not centered properly in the begining.

If the sample is a powder, it could be due to the movement of individual particles in magnetic field.

Hello,

So from the responses I see that the samples were not fixed properly when they were being investigated. These experiments were done in University of Western Australia, Perth where one of my colleague is working as a visiting scientist. When he raised the same question over there, they told that this could be due to the presence of multiple phases in the sample rather than a single phase. Could that be a reason?

I propose that the colleagues who gave that answer also give an explanation of the meachanism linking the presence of multiple phases to the observed measurements. (I'll be curious to hear about the answer. Since the curves apear almost saturated at high fields I see no room for any such kind of explanation.)

Yes Prof Kai,

I have sent them a mail stating the responses i received from Research Gate, Looking forwards for their mail.

Helo Prof Kai,

Jus got the information that there is a small problem with the instrument that they have and is due to the remanant magnetic field from the SQUID instrument itself

I had the same shape of loop on VSM when sample was decentred in magnetic field - sample was shift in direction of one of poles

According to me, its purely sample mounting problem. The sample has to be properly centered and sticked properly, I too experienced the same. I repeated the measurement again with proper sticking and the split wasn't there.

Secondly, about the multiple phases , if at they are present they should be visible in the other quadrants also, but in your case its not present.Hence I feel that it could be only due to sample mounting

When changing the direction of the field sample has been package elaboration and therefore there is a split line in this area. This is normal and often does happen.