Can Ferromagnetism Be Proven in Trapped Air?

[Pythagorean]

Is it possible to saturate an air core? Would you have to trap the air for this to work. Are domains a meaningless concept in a fluid, even if it's trapped? (i.e. it can still circulate in it's 'prison').

 

[berkeman]

Is it possible to saturate an air core? Would you have to trap the air for this to work. Are domains a meaningless concept in a fluid, even if it's trapped? (i.e. it can still circulate in it's 'prison').

I don't believe you can talk about saturation unless the core is ferromagnetic in nature. Not sure about paramagnetic and diamagnetic materials, but AFAIK, air is not magnetic.

 

[Pythagorean]

I don't believe you can talk about saturation unless the core is ferromagnetic in nature. Not sure about paramagnetic and diamagnetic materials, but AFAIK, air is not magnetic.

but are any materials truly non-magnetic?

I've always had this kind of philosophy (not assuming that it's correct, but it's my working philosophy for now) that there are no absolutes in nature. As an example, there's no perfect conductors or perfect insulators... everything is somewhere in between.

Note: I'm a hybrid physicist-engineer, so I tend to get completely different answers depending on which flavor of professor I ask these questions.

 

[berkeman]

I believe that you will measure the same inductance whether an "air core" inductor is in air or in a vacuum, but I haven't tried the experiment.

As for non-magnetic materials I'm thinking now about large MRI magnets and Fusion confinement magnets... Seems like the air around them (well, until the Fusion chamber is pumped down) isn't disturbed by those high fields. Interesting question, though.

 

[Bob S]

I don't believe you can talk about saturation unless the core is ferromagnetic in nature. Not sure about paramagnetic and diamagnetic materials, but AFAIK, air is not magnetic.

This gas is ferromagnetic. See
www.bit.ly/119g0V
or
http://www.sciencemag.org/cgi/content/full/sci;325/5947/1521
Bob S

 

[Pythagorean]

This gas is ferromagnetic. See
www.bit.ly/119g0V
or
http://www.sciencemag.org/cgi/content/full/sci;325/5947/1521
Bob S

Wait a minute... so ferromagnetism hasn't been proven yet?!

Good find.

edit: nevermind, poor wording:

"Ketterle and company weren't able to spot individual domains of alignment, which would be incontrovertible proof of ferromagnetism"

I'm guessing ferromagnetism is the observation, and this sentence is trying to say that there's no proof that Stoner's model necessarily leads to that observation.