Best core material would be for an electromagnet

[Phaedrus]

Wondering if anyone can give me a clue as to where I might look for information on what the best core material would be for an electromagnet if price were not an issue.

I need as much magnetic strength as possible for between 3-9 volts DC. At between 80-160Hz.

Basically this is a solenoid that moves an armature bar attached to a spring.

Corrosion is not an issue.
Price is not an issue.
Only efficiency.
Soft iron is usually the first choice but I'm looking for something at the top end of performance.
Thanks
If there is a better forum to ask this question under please let me know.

 

[Phaedrus]

Maybe calling it a "relay" is more accurate. Anyway the core material will be wrapped with magnet wire which will move an armature bar when on...which will open the circuit releasing the armature bar to its normal position which closes the circuit and starts the process over again...only this will be going 80-160 Hz...depending on the spring setup.
like this
http://img37.imagevenue.com/img.php?image=33026_relay1_122_401lo.jpg"
hope that worked

 

[vadslram]

Looks like a buzzer to me
Let's see I know your looking for a traction magnet and..
..
..
that's about it

BUT
http://www.cmispecialty.com/data-sheets.cfm"
This place specializes in it so they should know what you want.