Can spin valves be reliably deposited for magnetic recording applications? (invited)

Abstract

The tolerance of the expected read-back signal of spin valve giant magnetoresistance based structures to varying deposition and process conditions are described. We determine if spin valves can be produced reliably, and evaluate which thicknesses and properties are most critical. First, the dependence of spin valve properties on layer thickness are experimentally determined. Next, the variation of read-back signal and transfer curve characteristics with spin valve properties is calculated from micromagnetic modeling. Finally, these are convolved with the expected reproducibility of layer thickness to obtain an effective “yield” of structures within 10% of the mean amplitude. We find that spin valves can be reliably deposited, with “yields” well in excess of 90% likely.

Domain wall asymmetries in Ni81Fe19/NiO: proof of variable anisotropies in exchange bias systems

“…Exchange biased magnetic multilayers are one of the key components in current high-sensitivity magneto-resitive devices [1]. The exchange bias effect is associated with a magnetic loop shift [2] that occurs in coupled ferromagnetic/antiferromagnetic (F/AF) thin films.…”

Effects of controlling Cu spacer inter-diffusion by diffusion barriers on the magnetic and electrical stability of GMR spin-valve devices

“…To interpret the current shunting path model, two physical prerequisites, which are the lower activation energy of Cu compared to that of NiFe or Co [13] and the ''current sinking effects'' describing that more than 2/3 of applied current can flow through the Cu spacer in the NiFe/(Co)/Cu/(Co)/NiFe MMLDs due to the film resistivity difference between the NiFe (or Co) and Cu layers, should be considered [19]. According to Zhang's report [20] and Chang's calculation [21], the suddenly increased local temperature at a void site due to the ''current crowding effect'' would be high enough to cause the local melting of Cu spacer in the NiFe/ Cu/NiFe MMLDs.…”

“…NiFe/Cu/NiFe(Ni 81 Fe 19 )/(Mn-based anti-ferromagnetic layer, Mn-AFM) exchange-biased GMR (EBGMR) spin-valves (SV) have been paid a considerable attention in the various metallic spintronics devices such as a GMR magnetic read sensor and an in-vitro GMR biosensor [1][2][3] due to a high sensitivity at a lowswitching magnetic field and an extremely small hysteresis [4]. However, as the device size has been dramatically scaled-down to achieve an extremely high-information storage density and to realize an ultra large-scale integrated sensor array, the operating current density allowing for a reasonably high SNR (Signal-toNoise Ratio) is subsequently increased beyond J=1 Â 10 8 A/cm 2 [5].…”

Meeting the process challenges for spin-valve fabrication on an industrial scale

“…2 A crucial issue in this industrialization process is the availability of a reliable deposition process capable of depositing spin-valve GMR multilayers on substrates as used in industrial wafer processing with good uniformity, controllability and repeatability while achieving all the other film properties. 3 Magnetic multilayered structures such as GMR materials distinguish themselves from conventional thin film materials in two aspects: ͑1͒ The thickness of the individual layers is in the range of 10-100 Å, which is one or more orders of magnitude lower than most thin film materials, and ͑2͒ the GMR effect is a synergetic effect resulting from the interaction between the different layers. The quality of the interfaces between the different layers is of prime importance.…”