In magnetic read heads based on bottom spin valves the preferred structure
is for the longitudinal bias layer to be in direct contact with the free
layer. Such a structure is very difficult to manufacture. The present
invention overcomes this problem by introducing an extra layer between
the bias electrodes and the free layer. This layer protects the free
layer during processing but is thin enough to not interrupt exchange
between the bias electrodes and the free layer. In one embodiment this is
a layer of copper about 5 .ANG. thick and parallel exchange is operative.
In other embodiments ruthenium is used to provide antiparallel exchange
between the bias electrode and the free layer. A process for
manufacturing the structure is also described.