We have developed a technique to measure magnetic field of a write head. This technique is based on modified transmission electron microscopy (TEM). A patterned electron beam is projected to a head surface and distorted by magnetic field. Magnetic field distribution is obtained as a tomography image of a distorted pattern image.
Beginning from the study of reproducibility of electric contact between the wafer probe and the RW wire, equivalent circuit parameters of RW-wires were extracted as ; Low frequency inductance of a pair of W- or R- wire was 30nH, which means each wire has inductance of 15nH or less. Low frequency resistance was 5Ω, showing the resistance of each wire as 2.5Ω. Stray capacitance were 2-3 pF at low frequencies. Resonance frequency was 2GHz. Cross-talk model is also discussed.
High track density perpendicular SPT head is investigated by using 3-D finite element analysis. By assuming the side shield cores, the stray field can be decreased greatly when the density of 200Gb/in^2 (100nm write track width) is assumed. It is noted that the value of (stray field at adjacent track) / (recording field on track) can be reduced greatly with the side yoke shields as noted in 1Tb/in^2 analysis. To compensate the decrease of write field, increasing the main pole thickness is the most effective.
A front-yoke stacked-type TMR (Tunneling MagnetoResistive) head has an advantage of lower noise with a large size of the TMR element. The head has a symmetrical structure to the element, and produces Lorentzian waveforms without any distortion in combination with perpendicular magnetic recording media. Therefore, a conventional signal processor is applicable to the head. However, there is a crucial issue of crosstalk from adjacent tracks. This paper describes the design and performance of the front-yoke stacked-type TMR head. Three-dimensional magnetic field calculations of some read-out characteristics were carried out, and it was found that an effective method to increase signal output and decrease crosstalk from adjacent tracks.
We compared specular spin-valve films with an Fe_<50>Co_<50> nano-oxide layer (NOL) and a Co_<90>Fe_<10> NOL in a pinned layer, prepared by natural oxidation and ion-assisted oxidation (IAO). With small oxygen exposures during the oxidation for the Fe_<50>Co_<50> NOL by IAO, good ferromagnetic coupling through the NOL and high specularity at the NOL interface were concurrently obtained. On the other hand, natural oxidation did not cause large MR enhancement for either the Co_<90>Fe_<10> or Fe_<50>Co_<50> NOLs, and the Co_<90>Fe_<10> NOL by IAO caused weak magnetic coupling through the NOL, resulting in a small MR ratio. The Fe_<50>Co_<50> NOL for small oxygen exposures is a good candidate for a final specular spin-valve film head for 100-Giga-bit per square inch recording.
In this report we present a method improving GMR characteristics by replacing the ferromagnetic materials of the metal-based spin-valves in current-perpendicular-to- plane (CPP) geometry. AΔR (the product of the element area, A, and the change in resistance, ΔR) was investigated for three kinds of ferromagnetic materials : Co_<90>Fe_<10> (material A), Fe_<50>Co_<50> (material B), and Fe_<50>Co_<50> with 0.13 nm Cu layers (material C). AΔR is 1.0 mΩμm^2, 1.6 mΩμm^2, and 2.9 mΩμm^2 for materials A, B, and C, respectively. Simple analysis using the Valet-Fert model leads to two results. The first is that both the spin-dependent interface and bulk resistance are enhanced when material A is replaced by material B. The second is that the spin-dependent bulk resistance is increased when material B is replaced by material C. These results suggest the possibility of increasing AΔR without increasing the element resistance AR of spin valves in CPP geometry.
July 14, 2017 Due to the maintenance‚following linking services will not be available on Jul 27 from 10:00 to 15:00 (JST)(Jul 27‚ from 1:00 to 6:00(UTC)). We apologize for the inconvenience. a)reference linking b)cited-by linking c)linking to J-STAGE with JOI/OpenURL
July 03, 2017 There had been a service stop from Jul 2, 2017, 8:06 to Jul 2, 2017, 19:12(JST) (Jul 1, 2017, 23:06 to Jul 2, 2017, 10:12(UTC)) . The service has been back to normal.We apologize for any inconvenience this may cause you.
May 18, 2016 We have released “J-STAGE BETA site”.
May 01, 2015 Please note the "spoofing mail" that pretends to be J-STAGE.