Magnetoresistive head having controlled reproduction output characteristics

DETAILED DESCRIPTION The present invention provides an MR head, which is suitable for reproducing information recorded with a high density on a recording medium.
The present invention also provide an MR head capable of giving a reproduction output with an increased signal-to-noise (S/N) ratio.
The inventors of this invention have carried out experiments described below to study relations between the gap length of the MR head and the sense current characteristics (i.
e.
reproduction output voltage versus operation current characteristics) as well as relations between the magnetostriction constant of the MR element of the MR head and the sense current characteristics, as typically shown in FIGS.
6 and 7.
In order to perform high density information recording, it is necessary to decrease the electromagnetic converting gap length in the magnetic head for the purpose of increasing the reproduction output and for the resolving power and improving frequency characteristics.
For the MR head reproducing information recorded at such a high density, it is necessary to make the first insulating layer 2 and the second insulating layer 5 thin.
However, when the thickness of the first insulating layer 2 and the second insulating layer 5 vary, the magnetoresistance between the MR element 4 and the bias conductor 3 varies and thus the bias magnetic field H.
sub.
B applied to the MR element 4 varies.
For this reason, the operation point of the signal magnetic field in the .
DELTA.
R-H curve, indicated in FIG.
2, varies and the sense current characteristic curve, indicated in FIG.
3, varies as well.
In this way, it can be said that there is a close relationship between the electromagnetic converting gap length and the sense current characteristics.
FIG.
6 shows the sense current characteristics, the parameter being the electromagnetic converting gap length G with a magnetostriction constant .
lambda.
=0 for the MR element (made of an alloy Ni 82% -Fe 18%).
The layer thickness of the MR element was 40 nm; the bias conductor was constituted by a Ti layer 135 nm thick, and the first insulating layer was 0