Co2MnGe-based current-perpendicular-to-the-plane giant-magnetoresistance spin-valve sensors for recording head applications

Abstract

Magnetic and magnetotransport properties of current-perpendicular-to-the-plane (CPP) giant-magnetoresistance (GMR) spin-valve sensors containing the Heusler alloy Co2MnGe are presented. The geometrical and head integration constraints which exist for recording head applications are discussed and dictate various design compromises which determine the final device properties. Here we show that even for small total sensor thicknesses 400 Å and anneal temperatures < 250 °C we can obtain CPP-GMR signal levels up to ΔRA = 4 mΩ-μm2 at room temperature when inserting Co2MnGe in both the free layer and reference layers of the spin valve. Output levels increase to 10 mΩ-μm2 when reducing the temperature below 100 K, demonstrating the strong temperature dependence of the spin-dependent scattering in the Co2MnGe-based magnetic layers.

Enhanced half-metallicity of off-stoichiometric quaternary Heusler alloy Co2(Mn,Fe)Si investigated through saturation magnetization and tunneling magnetoresistanc

“…24 Fe 0. 16 Si 0.84 ) electrodes through the Fe composition (β ) dependence of the TMR ratio of CMFS MTJs that have Co 2 (Mn α Fe β )Si 0.84 electrodes with a constant (α + β ) value of 1.40 (series-B CMFS MTJs) [47]. These TMR ratios are significantly higher than those obtained for CMS MTJs that have Mn-rich CMS electrodes [10].…”

“…The enhancement in the TMR ratio for the MTJ with Co 2 Mn 1.24 Fe 0. 16 Si 0.84 electrodes (δ = 1.40) of up to 2610% at 4.2 K and μ s being close to its half-metallic value can be explained by the half-metallicity being retained for δ-rich CMFS, with a small amount of Fe replacing Mn, wherein residual Co Mn/Fe antisites are further suppressed by the δ-rich composition. Section IV summarizes our results and concludes the paper.…”

“…Accordingly, HMFs are seen as one of the most suitable spin source materials for spintronic devices. Co-based Heusler alloys (Co 2 Y Z, where Y is usually a transition metal and Z is a main group element) [4] are among the most extensively applied to spintronic devices, including magnetic tunnel junctions (MTJs), in particular those with a MgO barrier [5][6][7][8][9][10][11][12], and giant magnetoresistance (GMR) devices [13][14][15][16][17][18], and to spin injection into semiconductors [19][20][21][22][23][24][25]. This is due to the theoretically predicted half-metallicity for many of them [26][27][28] and their high Curie temperatures, which are well above room temperature (RT) [29].…”

Realization of high quality epitaxial current- perpendicular-to-plane giant magnetoresistive pseudo spin-valves on Si(001) wafer using NiAl buffer layer

“…11 Such a high MR output in a low resistance device has already satisfied the MR performance required for the areal density of 2 Tbit/in 2 according to the simulation by Takagishi et al 7 However, all of these high MR outputs have only been demonstrated for the epitaxial CPP-GMR pseudospin-valves (PSVs) grown on unpractical MgO single crystalline substrates, which are too expensive for mass production and incompatible with the current semiconductor industry processes. On the other hand, for industrial viability, polycrystalline CPP-GMR devices that were grown on thermal-oxidized Si substrate have been used, [12][13][14] but unfortunately, the MR output of polycrystalline devices is much lower than those of epitaxial devices that were grown on MgO substrates. The existence of grain boundary and inferior layer roughness is considered to be the possible reasons for such a large discrepancy of MR outputs between polycrystalline and single crystalline (epitaxial) devices.…”

Effect of CoFe insertion in Co2MnSi/CoFe/n-GaAs junctions on spin injection properties

“…These alloys have been extensively applied to spintronic devices, including magnetic tunnel junctions (MTJs) [13][14][15][16][17][18] and giant magnetoresistance (GMR) devices. [19][20][21][22][23] We recently demonstrated high tunnel magnetoresistance (TMR) ratios of up to 1995% at 4.2 K and up to 354% at 290 K in Co 2 MnSi/MgO/Co 2 MnSi MTJs with Mn-rich Co 2 MnSi electrodes. 18 The observed high TMR ratios for MTJs with Mn-rich Co 2 MnSi electrodes are attributed to suppressed Co Mn antisites, which leads to the enhanced half-metallicity through a reduced density of minority-spin in-gap states around E F .…”