cocrta as described in journal of magnetic society of japan vol 25 no 4 2 pp539 542 2001 co fe and ni are typical ferromagnetic materials to obtain longitudinal or perpendicular magnetic characteristics a combination of these ferromagnetic materials and other materials together appropriate seed layer and deposition for example cr cocrpt where cr is underneath gives a longitudinal film and ti cocrnb gives a perpendicular film theoretically these are subject to the following relationship where ku is the uniaxial anisotrophy constant and ms is saturation magnetisation fig5 a shows a magneto resistance mr sensor 207 comprising magneto electrical material in this case gmr and which has an exchange layer 207 e a pinned layer 207 p a spaced layer 207 s and a free layer 207 f the exchange layer 207 e is for making an exchange coupling with the pinned layer when an antiferromagnetic film eg ptmn is properly deposited next to ferromagnetic film e gco so called exchange coupling occurs as a consequence the magnetisation direction of the ferromagnetic film is aligned and fixed unless a large external magnetic filed is applied the coupled ferromagnetic film is known as the pinned layer in gmr tmr stacks and comprises a material having an antiferromagnetic property for example ptmn in antiferromagnetic materials the magnetic moments of adjacent atoms point in different directions and thus there is no net macroscopic magnetic moment in the material the pinned layer 207 p is.