Magnetoresistance Ratio and Resistance Area Design of CPP-MR Film for 2–5 $\hbox{Tb/in}^{2}$ Read Sensors

CPP-GMR study of half-metallic full-Heusler compound Co2(Fe,Mn)Si

“…The slight shifting of peak position between I and II might be related with Mn-diffusion into Ag spcer/buffer/capping layers since Mn is relatively easily diffused into Ag compared with Fe, i.e., the fewer amount of Mn is preferable to have an endurance for higher annealing temperature. In the sample of series II at x = 0.5, we observed the highest MRint of 55% and ΔRA of 17.2 mΩ•µm 2 , which satisfies required MR and RA for next generation read sensor for HDD with an areal density of 2 Tbit/inch 2 reported by Takagishi et al 28) Figure 3(a) shows annealing temperautre Tann dependence of MRint for Co2Fe0.5Mn0.5Si(20)/Ag(5)/ Co2Fe0.5Mn0.5Si (3) devices. The previous result in CMS/Ag/CMS is also plotted for comparison.…”

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

“…[1][2][3] The demand of higher areal density exceeding 2 Tbit/in 2 in hard disc drives (HDDs) highlights current-perpendicularplane (CPP)-GMR devices as a potential successor of the present tunneling magnetoresistive (TMR) device for next generation read head sensors due to its intrinsically low resistance area product (RA) for higher frequency responses. [4][5][6][7] Recently, substantial large MR ratios at room temperature (RT) were realized in fully epitaxial CPP-GMR devices with the usage of the Co-based Heusler alloys such as Co 2 MnSi (CMS), 8 Co 2 Mn(Ga 0.25 Ge 0.75 ) (CMGG), 9 Co 2 (Fe 0.4 Mn 0.6 )Si (CFMS), 10 and Co 2 Fe(Ga 0.5 Ge 0.5 ) (CFGG). 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.…”

“…[4][5][6][7] Recently, substantial large MR ratios at room temperature (RT) were realized in fully epitaxial CPP-GMR devices with the usage of the Co-based Heusler alloys such as Co 2 MnSi (CMS), 8 Co 2 Mn(Ga 0.25 Ge 0.75 ) (CMGG), 9 Co 2 (Fe 0.4 Mn 0.6 )Si (CFMS), 10 and Co 2 Fe(Ga 0.5 Ge 0.5 ) (CFGG). 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.…”

Enhancement of L2 1 order and spin-polarization of Heusler alloy Co 2 MnSi thin film by Ag alloying

“…Recently, the CPP-GMR devices using Heusler alloys regained strong interest as a potential alternative for the MgO based TMR sensors for read head applications in hard disk drives (HDD) due to the low device resistance obtained from the all metallic layers structure [19]. However, DRA of beyond 10 mX lm 2 must be obtained at low annealing temperature below 350°C in practical devices due to the poor thermal tolerance of a permalloy shield.…”

“…The half-metallic band gap sensitively changes depending on the degree of chemical disorder [18]; hence, obtaining high degree of L2 1 order is essential to achieve the half-metallicity at room temperature. Although the half-metallic band gap in the L2 1 structure is theoretically predicted to be preserved in the B2 structure in some of Co 2 FeZ and Co 2 MnZ-types alloys, significant improvement of DRA with increasing the degree of L2 1 -order by post-annealing above 500°C was reported in the CFMS/Ag/CFMS [5] and CFGG/Ag/CFGG [7] tri-layer structures.Recently, the CPP-GMR devices using Heusler alloys regained strong interest as a potential alternative for the MgO based TMR sensors for read head applications in hard disk drives (HDD) due to the low device resistance obtained from the all metallic layers structure [19]. However, DRA of beyond 10 mX lm 2 must be obtained at low annealing temperature below 350°C in practical devices due to the poor thermal tolerance of a permalloy shield.…”