US 11,887,635 B2
Adaptive bias control for magnetic recording head
Glen Garfunkel, San Jose, CA (US); Yan Wu, Cupertino, CA (US); Wenyu Chen, San Jose, CA (US); Kunliang Zhang, Fremont, CA (US); Min Li, Fremont, CA (US); and Shohei Kawasaki, Sunnyvale, CA (US)
Assigned to Headway Technologies, Inc., Milpitas, CA (US)
Filed by Headway Technologies, Inc., Milpitas, CA (US)
Filed on Jul. 1, 2022, as Appl. No. 17/856,585.
Application 17/856,585 is a division of application No. 17/081,235, filed on Oct. 27, 2020, granted, now 11,380,355.
Prior Publication US 2022/0335969 A1, Oct. 20, 2022
Int. Cl. G11B 5/39 (2006.01); G11B 5/00 (2006.01); G11B 5/48 (2006.01)
CPC G11B 5/3932 (2013.01) [G11B 5/3909 (2013.01); G11B 5/3912 (2013.01); G11B 5/3967 (2013.01); G11B 5/4826 (2013.01); G11B 5/4833 (2013.01); G11B 2005/0008 (2013.01); G11B 2005/0018 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A magnetic read head structure, comprising:
(a) a tunneling magnetoresistive (TMR) sensor formed on a bottom shield and with a front side at an air bearing surface (ABS), and wherein the TMR sensor comprises a capping layer formed on a free layer (FL), and a reference layer (RL) separated from the FL with a tunnel barrier laver, and wherein the TMR sensor has a backside that extends from a top surface on the capping layer to a top surface of the bottom shield, and wherein the FL with has a first magnetization substantially in a first cross-track direction, and has two sidewalls formed equidistant from a center plane that bisects the TMR sensor;
(b) the bottom shield;
(c) a longitudinal (L) biasing layer that is adjacent to each of the two FL sidewalls, and each L biasing layer has a front side at the ABS, a second magnetization in the first cross-track direction, and provides a bias field to stabilize the first magnetization in the free layer (FL);
(d) a permanent magnet (PM) layer with a front side that faces a backside of the FL and is a greater distance from the ABS than the TMR sensor backside, a width that is substantially equal to a width of the FL, and separated from the FL by an insulation layer having a top surface that is coplanar with the capping layer top surface, and wherein the PM layer has a magnetization that is orthogonal to the ABS and initialized in a direction that adjusts a FL bias point so that the absolute value of TMR sensor asymmetry is reduced and is closer to 0% than in the absence of the initialized PM layer; and
(e) a top shield that contacts a top surface of the TMR sensor.