The magnetic strips on credit cards can become demagnetized. what type of magnet are they?

I think you're fishing for "temporary magnet" or something like that,
but I don't agree with it. 

Credit card strips, refrigerator magnets, recording tape, bar magnets,
and big heavy horseshoe magnets are permanent magnets ... you don't
have to keep an electric current circulating around them to make them
magnetic. 

But that doesn't mean that they stay magnetic no matter WHAT you do
to them.  They can be DEmagnetized by being heated, dropped on the
floor, hit with a hammer, or in the presence of another, stronger magnet.