Flux diode, magnetic semiconductors

[Salvador]

So I was reading about magnetic semiconductors and I got confused so can you please clarify I will ask a question that is made up of two parts.
Magnetic semiconductors are ...
a) devices that alter or switch on/off electric current flow depending on the magnetic field strength etc applied OR
b) devices that alter the magnetic flux or the field itself and are controlled with electric current or potential themselves?

I kinda think the second B one is closer to truth because as the word implies " magnetic" semiconductor would be something like a transformer core that has flux through it but with the ability to control the amount of flux passing through it much like a transistor controls the amount of current through it, correct?If these devices are possible then I have a further question would an electric field semiconductor be possible , like for example a device which can control the electric field through it like a capacitor with a special dielectric that could be altered to alter the field strength and the capacitance?

And finally could a magnetic diode be possible , like a material that allows magnetic field lines to travel only one way ? Like when you attach N-S to the device the magnets stick but if you put them S-N the magnets can't feel each other? Or for example a material taht could cancel out or rather reroute the field between opposite poles but let through the field from alike poles?

thank you.

 

[davenn]

a) devices that alter or switch on/off electric current flow depending on the magnetic field strength etc applied OR

These devices are called Hall effect devices ( google it) and come in the 2 styles
1) the current flow through them varies with the magnetic field strength
2) the current is switched depending on if there is a magnetic field present or not

your b application I have never heard ... don't know if it exists or not ... some one else may be able to commentDave

 

[Salvador]

well yes I know hall effect devices but these are different. well anyways i hope someone could give me some insight on the other part of my question

 

[davenn]

what do you mean different ?

i hope someone could give me some insight on the other part of my question

then you may have to be more specific ... links to what you have been reading etcDave

 

[Salvador]

http://en.wikipedia.org/wiki/Magnetic_semiconductor

basically a better explanation of the above link would come in handy.
and what i originally thought by saying devices that alter the magnetic flux is well normally a transistor is a switch for current , but here we have a device which is a switch for field flux lines in a material , for example we can alter the electric field by changing the type of dielectric between capacitor plates , could we also vary the flux through a inductor core or similar by varying the properties of a material being inserted in the core or maybe the core itself is that material.

and a more crazy question that came in mind while reading about this , imagine two permanent magnets , is there the slightest chance that there is a material which allows the magnets to "feel" each other when they are placed with the like poles together with the material in the middle ,and not "feel" each other when they are placed with opposite poles facing each other, again with the material in the middle.?if there would be a way to achieve this property it would make some cool things possible.

 

[Salvador]

anyone?