Superconductors as electromagnets

[Conk]

Can a superconductor be used as the base of an electromagnet, or does it not work since the superconductor is already magnetized? I know they have zero resistance for conductivity, but this nuance is beyond me.

[jake-the-peg]

The worlds largest atom smashers are powered by superconducting magnets.

The use of superconducting magnets can be a problem, firstly because you need to use liquid helium which can be dangerous because of the very low temperatures invoved.

You can't just pour a beaker of liquid helium like liquid nitrogen as it would freeze the air it came into contact with.

Secondly if the temperature raises above the critical superconducting temperature the magnet suddenly ceases to become superconducting "quenches" this can have violent consequences.

A Quench test at Cern last year wrecked a portion of the experiment and put them back a year.

More on superconducting magnets here:
http://en.wikipedia.org/wiki/Superconducting_m agnet