Abstract: A magnetic material of at least two component parts arranged to have respective structures which mutually are not homogenous, the structure of one part cooperating with the structure of the other to assist the magnetostrictive behaviour of the material. The cooperation can be the structure of one part altering the atomic spacing of the other part. The alteration can be an increase from the usual atomic spacing. There can be contiguous component parts and the cooperation can be a pseudo free surface on at least one part or a reduced restriction of the local moment otherwise achieved by the contiguous component parts. A component can be at least partly an alloy and the alloy can have a ratio other than the usual one for the alloy. One of the components can be non-magnetic.