Tapered junction shield for self-compensation of asymmetry with increasing aspect ratio for tunneling magneto-resistance (TMR) type read head

A read head, comprising:

• (a) a tunneling magnetoresistive (TMR) sensor structure that has a bottom surface formed on a bottom shield, a top surface contacting a top shield, and two sidewalls connecting the top and bottom surfaces, and comprising a free layer (FL) having a FL width (FLW) and a magnetization in a cross-track dimension between the sidewalls, and a stripe height (SH) between a FL front side at an air bearing surface (ABS) and a FL backside;
• and
• (b) a junction shield (JS) structure formed adjacent to each of the two sidewalls, and that provides a longitudinal bias to the FL magnetization, comprising:
• (1) a lower JS layer with a bottom surface aligned orthogonal to the ABS, and a tapered top surface formed at a taper angle with respect to a first plane that is aligned orthogonal to the ABS and parallel to the lower JS layer bottom surface, wherein a thickness of the lower JS layer decreases with increasing height from the ABS such that there is a first thickness (t1) at the ABS that is greater than a second thickness (t2) at a lower JS layer backside, and a first magnetization (of magnitude JS1) therein is parallel to the FL magnetization;
• (2) a first antiferromagnetic coupling (AFC) layer having a substantially uniform thickness on the lower JS layer;
• and
• (3) a second JS layer formed on the first AFC layer, and wherein a thickness of the second JS layer increases with increasing height from the ABS such that there is a fourth thickness (t4) at the ABS that is less than a third thickness (t3) at a second JS layer backside, where (t1+t4)=(t2+t3), and wherein a second magnetization (of magnitude JS2) is aligned anti-parallel to JS1 to provide a net longitudinal bias determined by a difference (JS1−JS2).