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Method and system for providing a read transducer having symmetric antiferromagnetically coupled shields

  • US 10,074,387 B1
  • Filed: 12/21/2014
  • Issued: 09/11/2018
  • Est. Priority Date: 12/21/2014
  • Status: Active Grant
First Claim
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1. A magnetic read transducer having an air-bearing surface (ABS), comprising:

  • a first antiferromagnetically-coupled (AFC) shield, the first AFC shield including a first ferromagnetic layer, a second ferromagnetic layer and a first nonmagnetic spacer layer between the first ferromagnetic layer and the second ferromagnetic layer, the first ferromagnetic layer having a first saturation magnetization and a first thickness, the second ferromagnetic layer having a second saturation magnetization and a second thickness, wherein there is a first difference between the first ferromagnetic layer and the second ferromagnetic layer, the first difference including at least one of a difference between the first thickness and the second thickness or a difference between compositions of the first ferromagnetic layer and the second ferromagnetic layer;

    a read sensor, the second ferromagnetic layer being between the read sensor and the first ferromagnetic layer; and

    a second AFC shield, the second AFC shield including a third ferromagnetic layer, a fourth ferromagnetic layer and a second nonmagnetic spacer layer between the third ferromagnetic layer and the fourth ferromagnetic layer, the third ferromagnetic layer being between the read sensor and the fourth ferromagnetic layer, the third ferromagnetic layer having a third saturation magnetization and a third thickness, the fourth ferromagnetic layer having a fourth saturation magnetization and a fourth thickness, wherein there is a second difference between the third ferromagnetic layer and the fourth ferromagnetic layer that corresponds to the first difference such that the second AFC shield is a mirror image of the first AFC shield,wherein the second saturation magnetization multiplied by the second thickness matches the third saturation magnetization multiplied by the third thickness to within twenty percent and the first saturation magnetization multiplied by the first thickness matches the fourth saturation magnetization multiplied by the fourth thickness to within twenty percent,wherein the second thickness is different from the third thickness and the second ferromagnetic layer is made of different materials than materials in the third ferromagnetic layer, or the first thickness is different from the fourth thickness and the first ferromagnetic layer is made of different materials than materials in the fourth ferromagnetic layer.

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