Thin film magnetic head having a variable thickness magnetic layer

A thin film magnetic head comprising:

• a first magnetic layer having a first pole portion and a first core portion;
• a second magnetic layer having a second pole portion and a second core portion, wherein the first pole portion and the second pole portion define a gap region between a first surface of the first magnetic layer and a second surface of the second magnetic layer in which the first surface and the second surface are parallel, the gap region being disposed so that a write magnetic field is generated adjacent the gap region;
• an indentation defined as a locally reduced thickness area in at least one of the first and the second pole portions, the locally reduced thickness area being provided in a pole portion adjacent to or within the gap region so that the indentation has a thickness which is less than the thickness of the rest of the pole portion and less than the thickness of the core portion;
• a gap layer separating the first magnetic layer and the second magnetic layer;
• one or more conduction coils provided between the gap layer and the first magnetic layer;
• one or more non-magnetic insulating layers provided between the gap layer and the first magnetic layer for protecting the conduction coils;
• and
• a projecting portion having a first edge and a second edge formed on a surface of at least one of the first or second pole portions of the first and second magnetic layers, respectively, the projecting portion protruding longitudinally from the surface of an associated pole portion;
• wherein the indentation separates the rear edge of the projecting portion from an associated core portion which is thicker than the projecting portion.

A thin film magnetic head comprising:

• a first magnetic layer having a first pole portion disposed adjacent a region in which a write magnetic field is generated;
• a gap layer contacting the first magnetic layer on a first side of the first pole portion, wherein a throat height zero position is defined at an inside edge of the area of contact between the gap layer and the first side of the first pole portion;
• a second magnetic layer having first and second sides, a second pole portion, and a core portion, the second magnetic layer contacting the gap layer at least on the first side of the second pole portion opposite and separated from the first side of the first pole portion by the gap layer, the second side having:
• a projecting portion having thickness in the range of 0.2-3.0 .mu.m, and
• an indentation defined as a locally reduced thickness area in the second magnetic layer, the indentation being located in the vicinity of the throat height zero position;
• at least one conduction coil provided between the first and the second magnetic layer;
• and
• at least one non-magnetic insulating layer provided between the first and the second magnetic layer for protecting the at least one conduction coil.

A thin film magnetic head comprising:

• a first magnetic layer having a first pole portion with a first thickness, a first core portion with a second thickness, and a depression formed therein having a thickness which is less than the first and second thicknesses;
• a second magnetic layer having a second pole portion and a second core portion;
• a gap layer formed between the first and second magnetic layers, the gap layer contacting both the first and the second magnetic layers at the first and second pole portions, wherein the depression in the first magnetic layer is disposed adjacent a portion of the gap layer which is in contact with both the first and second magnetic layers thereby causing magnetic saturation in the first magnetic layer to be isolated near the depression in the first magnetic layer;
• and
• a laminated structure comprising a plurality of coils and an insulating layer, the laminated structure being formed between the gap layer and the second magnetic layer.