No abstract

No abstract

No abstract

No abstract

We have realized a large magnetoresistance (MR) ratio of 10.2% by current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) spin-valve films having current-confined-path (CCP) structure formed by AlCu-NOL (nano-oxide-layer). CPP-GMR with conventional Co90Fe10 pinned and free layers showed an MR ratio and a ΔRA (the change of resistance area product) were 4% and 20mΩμm2, respectively, at a small RA (resistance area product) of 500mΩμm2. By replacing the Co90Fe10 layers by Fe50Co50 layers both for pinned and free layers, we have successfully realized a MR ratio and a ΔRA of 7.5% and 37.5mΩμm2, respectively, at a small RA of 500mΩμm2. Moreover, a large MR ratio of 10.2% and a large ΔRA of 418mΩμm2 were realized at a relatively large RA of 4100mΩμm2. This large MR ratio by using Fe50Co50 layers was due to a larger spin-dependent interface scattering factor γ of 0.72 for the interface between Fe50Co50 and Cu, which was improved from a γ of 0.62 for the interface between Co90Fe10 and Cu.

Articles you may be interested inStudy on the effect of ion beam bombardment during deposition on preferred orientation in rutile-type titanium dioxide films

A large output voltage of 0.7 mV at 1 mA charge current is demonstrated for all-metallic nonlocal spin valves using Co 2 (FeMn)Si Heusler alloy and Cu with a junction area of about 50 nm 2 . The output is attributed to the junction size reduction as well as to the high spin polarization in the Heusler alloy. An analysis using a one-dimensional model reveals that the spin diffusion length in the Cu layer shows no clear degradation even in the case of a 50 nm 2 junction. When the junction is reduced further to 10 nm 2 , an output voltage of about 10 mV is expected.© 2015 The Japan Society of Applied Physics F or high-density magnetic recording over 2 Tbit/in. 2 , the total thickness of a read sensor should be reduced to less than 20 nm. However, conventional spin valve sensors cannot meet this specification because of their thick stack of pinned magnetic and antiferromagnetic layers. Nonlocal spin valves (NLSVs), which have a lateral structure and use spin-accumulation effects, 1,2) are promising for solving this problem. The pinned/antiferromagnetic layer stack is placed outside the read gap area. The output voltage generated by a pure spin current is also preferable from the standpoints of electric circuit noise and reliability.One of the challenges for NLSV sensors is the small output voltage. It has been reported that the output (measured by the resistance change) of all-metallic NLSVs using NiFe wire ranges from a value below 1 m³ (submicrometer junction) to 9 m³ (50 nm junction). 3-9) All-metallic NLSVs using Heusler alloys, which have a higher spin polarization than NiFe, show an output of up to 17 m³. [10][11][12] From these results, it is effective to use the Heusler alloys with a reduced junction size for obtaining a high output. However, the reported outputs are still too low for application in read head sensors. NLSVs with a thin MgO layer between ferromagnetic (FM) and nonmagnetic (NM) wires are reported to have a large output of 400 m³ 13) However, a large junction resistance is not suitable for high-density high-speed hard disk drive applications.In this paper, attempts to increase the output of all-metallic NLSVs are reported. The junction size is reduced to 50 nm. Co 2 (FeMn)Si (CFMS) polycrystalline Heusler alloys 14,15) are used to increase spin polarization. Results are analyzed using a one-dimensional analytical model. The extensibility of this system to recording densities of over 2 Tbit/in. 2 is also discussed.Figure 1(a) shows a layout of a test chip. The widths of the NM wire (W N ), FM wires (W F ), and gap between the two FM wires (W gap ) were set to the same value. They were changed from 50 to 150 nm. The film stack at the FM/NM junction was Ta (2 nm)/Cu (10 nm)/Co 2 Fe 0.4 Mn 0.6 Si (6-20 nm)/ Cu (20 nm). The area around the junction was filled with a SiO 2 insulating layer.First, the FM wires were deposited by conventional magnetron sputtering at room temperature on a thermally oxidized Si substrate. The film stack was Ta (2 nm)/Cu (10 nm)/ Co 2 Fe 0.4 Mn 0.6 Si (6-20 nm)/Cu (20 nm)/...

We have developed the FeCo nanocontact magnetoresistance (NCMR) with spin-valve structure [H. N. Fuke et al., IEEE Trans. Magn. 43, 2848 (2007)] which exhibits up to a MR ratio of 11%–12% at a resistance area (RA) of 0.3–0.55 Ω μm2. The nanocontact configurations were estimated at about 2 nm in in-plane diameter, 1.2 nm in thickness, and 0.55% in density for a RA∼0.5 Ω μm2 film based on in-plane current distribution by conductive atomic-force microscopy cross sectional transmission electron microscope images of the NCMR. The origin of the NCMR was discussed by comparing magnetic field dependence of resistance, with micromagnetics simulation based on the diffusive MR theory. It is found that our NCMR cannot be explained by diffusive domain wall theory or bulk scattering in free and pinned layers. It is likely that a theory on the basis of a ballistic MR consideration is needed to interpret our MR origin.