TMR device with novel free layer structure
First Claim
1. A magnetoresistive element in a magnetic device, comprising:
- (a) a synthetic anti-parallel (SyAP) pinned layer;
(b) a free layer consisting of (CoFeTb/CoFeB)n, (CoFeTb/CoFeBTb)n,(CoFeTbL/CoFeB)n, or (CoFeTbL/CoFeBTb)n wherein n≧
2, L is one of Ni, Ti, W, Zr, Hf, or Nb and has a content greater than 0 atomic %, and each of said CoFeB or CoFeBTb layers has a greater thickness than each of said CoFeTb, or CoFeTbL layers in the free layer wherein a boron containing layer alternates with a non-boron containing layer, and all layers in the free layer have at least one non-magnetic element, and;
(c) a tunnel barrier layer having a first surface that contacts the SyAP pinned layer and a second surface that contacts a CoFeTb, or CoFeTbL layer in said free layer wherein said second surface is opposite said first surface.
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Accused Products
Abstract
A TMR sensor that includes a free layer having at least one B-containing (BC) layer made of CoFeB, CoFeBM, CoB, COBM, or CoBLM, and a plurality of non-B containing (NBC) layers made of CoFe, CoFeM, or CoFeLM is disclosed where L and M are one of Ni, Ta, Ti, W, Zr, Hf, Tb, or Nb. One embodiment is represented by (NBC/BC)n where n≧2. A second embodiment is represented by (NBC/BC)n/NBC where n≧1. In every embodiment, a NBC layer contacts the tunnel barrier and NBC layers each with a thickness from 2 to 8 Angstroms are formed in alternating fashion with one or more BC layers each 10 to 80 Angstroms thick. Total free layer thickness is <100 Angstroms. The free layer configuration described herein enables a significant noise reduction (SNR enhancement) while realizing a high TMR ratio, low magnetostriction, low RA, and low Hc values.
33 Citations
8 Claims
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1. A magnetoresistive element in a magnetic device, comprising:
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(a) a synthetic anti-parallel (SyAP) pinned layer; (b) a free layer consisting of (CoFeTb/CoFeB)n, (CoFeTb/CoFeBTb)n,(CoFeTbL/CoFeB)n, or (CoFeTbL/CoFeBTb)n wherein n≧
2, L is one of Ni, Ti, W, Zr, Hf, or Nb and has a content greater than 0 atomic %, and each of said CoFeB or CoFeBTb layers has a greater thickness than each of said CoFeTb, or CoFeTbL layers in the free layer wherein a boron containing layer alternates with a non-boron containing layer, and all layers in the free layer have at least one non-magnetic element, and;(c) a tunnel barrier layer having a first surface that contacts the SyAP pinned layer and a second surface that contacts a CoFeTb, or CoFeTbL layer in said free layer wherein said second surface is opposite said first surface. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A magnetoresistive element in a magnetic device, comprising:
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(a) a synthetic anti-parallel (SyAP) pinned layer; (b) a free layer consisting of (CoFeTb/[Co(100-X)FeX]100-YBY)n, (CoFeTb/CoFeBTb)n, (CoFeTbL/[Co(100-X)FeX]100-YBY)n, or (CoFeTbL/CoFeBTb)n wherein n≧
2, x=0 or 100 atomic %, y is from 10 to 40 atomic %, L is one of Ni, Ta, Ti, W, Zr, Hf, or Nb and has a content greater than 0 atomic %, and each of said [Co(100-X)FeX]100-YBY or CoFeBTb layers has a greater thickness than each of said CoFeTb, or CoFeTbL layers in the free layer wherein a boron containing layer alternates with a non-boron containing layer, and all layers in the free layer have at least one non-magnetic element, and;(c) a tunnel barrier layer having a first surface that contacts the SyAP pinned layer and a second surface that contacts a CoFeTb, or CoFeTbL layer in said free layer wherein said second surface is opposite said first surface.
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Specification