It depends on the currents inside a plasma and its density. Stable high current at high pressure is what you need for good ferromagnetic pieces magnetization.

Dear Diego.

Fe or Ni are ferromagnetic metals which reach a magnetization below their respective Curie temperatures. The plasma only can help to destroy their ferromagnetic order and never help it.

The speed of magnetization is suffiently more than the speed of heat propagation from a plasma to Fe(Ni) samples. Thus, high-current pulse discharge in convective dense medium might fit the idea.

Dear Daniel and Alexander,

Thanks, what I am thinking of is Fe/Ni grains in space and surrounded by the plasma environment provided by solar wind.

Does that make a difference in your answers? Any additional thoughts?

Thanks again,

Paul

Dear Diego, in this case I agree with Daniel. The magnetization is only possible near the Sun if there will be any man-made protection from solar radiation and long solar wind effect. Parker Solar probe is the good tool for such experiments.

Dear Diego,

The solar wind is not going to change anything with respect to my initial answer. The important is if the change of temperature could be enough high to change, but assuming you have it in the vacuum space the temperature would be much lower than their Curies temperatures. Thus the magnetization would kept fixed and without any trouble due to this solar wind.

Thank you both, this has been really helpful. The systems I am looking at reach temperatures of up to ~300K, which is way below Ni and Fe Curie temperatures. Tell me something else, how do I find out the magnetic field that a plasma magnetized piece of Fe/Ni can produce? Can you point me to some references I could read?

The measuring algorithm at a presence of external magnetic fields with unknown configurations may be as follows. Spherical Fe/Ni sample is placed in a magnetic shielded chamber after magnetization. High-sensitive Hall or magnetoresistive probe is used to measure magnetic induction around the sphere. Obtained data set is processed and analysed on PC. Remanence field may be obtained by the formula:

https://www.supermagnete.de/eng/faq/How-do-you-calculate-the-magnetic-flux-density#formula-for-sphere-magnet-flux-density

Dear Alexander, thanks, I was actually wondering if there was a theoretical expression that relates the plasma to the physical characteristics of the sample so that the magnetic field can be calculated.