The antimicrobial properties of the ceramic oxide you are referring to must be related to its catalytic properties, reducing the energy of the transition state along some reaction path which is detrimental to microbes. Viewed from this perspective, it may be helpful to consider the following publication, which is dedicated to Iron-containing enzymes (needless to say, Iron is ferromagnetic):

http://www.rsc.org/shop/books/2011/9781849731812.asp

I have had a brief look through some pages of this publication, and have noticed that spin configuration of molecules is indeed very important in some catalytic reactions.

Thank you, Behnam farid

You are welcome!