摘要:
A CPP MR sensor interposes a tapered soft magnetic flux guide (FG) layer between a hard magnetic biasing layer (HB) and the free layer of the sensor stack. The flux guide channels the flux of the hard magnetic biasing layer to effectively bias the free layer, while eliminating instability problems associated with magnetostatic coupling between the hard bias layers and the upper and lower shields surrounding the sensor when the reader-shield-spacing (RSS) is small.
摘要:
A magnetic sensor, formed from a pair of magnetically free layers located on opposing sides of a non-magnetic layer, and method for its manufacture, are described. Biasing these free layers to be roughly orthogonal to one another causes them to be magnetostatically coupled in a weak antiferromagnetic mode. This enables the low frequency noise spectra of the two free layers to cancel one another. Careful control of the SH/TW ratio is an important feature of the device.
摘要:
A magnetic sensor, formed from a pair of magnetically free layers located on opposing sides of a non-magnetic layer, and method for its manufacture, are described. Biasing these free layers to be roughly orthogonal to one another causes them to be magnetostatically coupled in a weak antiferromagnetic mode. This enables the low frequency noise spectra of the two free layers to cancel one another. Careful control of the SH/TW ratio is an important feature of the device
摘要:
A CPP MR sensor interposes a tapered soft magnetic flux guide (FG) layer between a hard magnetic biasing layer (HB) and the free layer of the sensor stack. The flux guide channels the flux of the hard magnetic biasing layer to effectively bias the free layer, while eliminating instability problems associated with magnetostatic coupling between the hard bias layers and the upper and lower shields surrounding the sensor when the reader-shield-spacing (RSS) is small.
摘要:
An annealing process for a TMR or GMR sensor having an amorphous free layer is disclosed and employs at least two annealing steps. A first anneal at a temperature T1 of 200° C. to 270° C. and for a t1 of 0.5 to 15 hours is employed to develop the pinning in the AFM and pinned layers. A second anneal at a temperature T2 of 260° C. to 400° C. where T2>T1 and t1>t2 is used to crystallize the amorphous free layer and complete the pinning. An applied magnetic field of about 8000 Oe is used during both anneal steps. The mechanism for forming a sensor with high MR and robust pinning may involve structural change in the tunnel barrier or at an interface between two of the layers in the spin valve stack. A MgO tunnel barrier and a CoFe/CoB free layer are preferred.
摘要:
A composite free layer having a FL1/insertion/FL2 configuration where a top surface of FL1 is treated with a weak plasma etch is disclosed for achieving enhanced dR/R while maintaining low RA, and low λ in TMR or GMR sensors. The weak plasma etch removes less than about 0.2 Angstroms of FL1 and is believed to modify surface structure and possibly increase surface energy. FL1 may be CoFe, CoFe/CoFeB, or alloys thereof having a (+) λ value. FL2 may be CoFe, NiFe, or alloys thereof having a (−) λ value. The thin insertion layer includes at least one magnetic element such as Co, Fe, and Ni, and at least one non-magnetic element. When CoFeBTa is selected as insertion layer, the CoFeB:Ta ratio is from 1:1 to 4:1.
摘要:
An insertion layer is provided between an AFM layer and an AP2 pinned layer in a GMR or TMR element to improve exchange coupling properties by increasing Hex and the Hex/Hc ratio without degrading the MR ratio. The insertion layer may be a 1 to 15 Angstrom thick amorphous magnetic layer comprised of at least one element of Co, Fe, or Ni, and at least one element having an amorphous character selected from B, Zr, Hf, Nb, Ta, Si, or P, or a 1 to 5 Angstrom thick non-magnetic layer comprised of Cu, Ru, Mn, Hf, or Cr. Preferably, the content of the one or more amorphous elements in the amorphous magnetic layer is less than 40 atomic %. Optionally, the insertion layer may be formed within the AP2 pinned layer. Examples of an insertion layer are CoFeB, CoFeZr, CoFeNb, CoFeHf, CoFeNiZr, CoFeNiHf, and CoFeNiNbZr.
摘要:
A composite free layer having a FL1/insertion/FL2 configuration is disclosed for achieving high dR/R, low RA, and low λ in TMR or GMR sensors. Ferromagnetic FL1 and FL2 layers have (+) λ and (−) λ values, respectively. FL1 may be CoFe, CoFeB, or alloys thereof with Ni, Ta, Mn, Ti, W, Zr, Hf, Tb, or Nb. FL2 may be CoFe, NiFe, or alloys thereof with Ni, Ta, Mn, Ti, W, Zr, Hf, Tb, Nb, or B. The thin insertion layer includes at least one magnetic element such as Co, Fe, and Ni, and at least one non-magnetic element selected from Ta, Ti, W, Zr, Hf, Nb, Mo, V, Cr, or B. In a TMR stack with a MgO tunnel barrier, dR/R>60%, λ˜1×10−6, and RA=1.2 ohm-um2 when FL1 is CoFe/CoFeB/CoFe, FL2 is CoFe/NiFe/CoFe, and the insertion layer is CoTa or CoFeBTa.
摘要:
A magneto-resistive device having a large output signal as well as a high signal-to-noise ratio is described along with a process for forming it. This improved performance was accomplished by expanding the free layer into a multilayer laminate comprising at least three ferromagnetic layers separated from one another by antiparallel coupling layers. The ferromagnetic layer closest to the transition layer must include CoFeB while the furthermost layer is required to have low Hc as well as a low and negative lambda value. One possibility for the central ferromagnetic layer is NiFe but this is not mandatory.
摘要:
A high performance TMR sensor is fabricated by employing a composite inner pinned (AP1) layer in an AP2/Ru/AP1 pinned layer configuration. In one embodiment, there is a 10 to 80 Angstrom thick lower CoFeB or CoFeB alloy layer on the Ru coupling layer, a and 5 to 50 Angstrom thick Fe or Fe alloy layer on the CoFeB or CoFeB alloy, and a 5 to 30 Angstrom thick Co or Co rich alloy layer formed on the Fe or Fe alloy. A MR ratio of about 48% with a RA of