Microstructure and magnetic properties of CoCr thin films formed on Ge layer

To improve the c-axis oriented columnar growth, the nucleation of CoCr crystals on various underlayers which are formed on substrates prior to CoCr alloy deposition is studied. Microstructures of vacuum deposited CoCr alloy films are examined by transmission electron microscopy (TEM). It is found that an amorphous-like Ge is a suitable underlayer material to prepare highly oriented CoCr films. Cross-sectional TEM study indicates that the CoCr film formed on Ge layer consists of pillarlike crystals grown vertically throughout the film thickness. The CoCr film formed on Ge layer has a large perpendicular magnetic anisotropy. The read-write (R/W) characteristics have been markedly improved using the highly oriented CoCr film and a very high recording density of D50=230 kFCI is achieved, The role of the Ge layer on nucleation of CoCr crystal is discussed.