A magnetoresistive head which has a high low resistance and a high MR ratio at
room temperature and a S/N ratio that does not decrease sharply upon application
of a bias voltage. The magnetoresistive head comprises a soft magnetic free layer,
a non-magnetic insulating layer, and a ferromagnetic pinned layer. The ferromagnetic
pinned layer may have a spin valve layer whose magnetization is fixed with respect
to the magnetic field to be detected, and the soft magnetic free layer permits
its magnetization to rotate in response to an external magnetic field, thereby
changing the relative angle with the magnetization of said ferromagnetic pinned
layer and producing the magnetoresistive effect. The absolute value of the magnetoresistive
effect has a peak at a temperature in the range from about 0 C. to 60
C. and for a bias voltage Vs (applied across said ferromagnetic pinned layer and
said soft magnetic free layer) in the range from +0.2 to +0.8 V and from -;0.8
to -;0.2 V. The above characteristics may be achieved if the ferromagnetic pinned
layer is formed from Fe3O4 or at least one oxide or compound
of Cr and Mn; the non-magnetic insulating layer is formed from at least one oxide
of Sr, Ti, and Ta; or the soft magnetic free layer is a CoFe alloy containing 70-100
atom % of Co, the ferromagnetic pinned layer is a CoFe alloy containing 0-70 atom
% of Co, and the non-magnetic insulating layer is formed from at least one oxide
of Sr, Ti, and Ta.
