PtMn single and dual spin valves with synthetic ferrimagnet pinned layers

Abstract

Spin valve films with the PtMn/Co/Ru/Co synthetic ferrimagnet pinned layer, in which the magnetization of the two Co layers is strongly coupled in an antiparallel orientation and the magnetization direction of one of the Co layers is pinned by unidirectional exchange coupling with PtMn, were investigated. PtMn synthetic ferrimagnet pinned layers were demonstrated to exhibit strong unidirectional exchange field Hex exceeding 2500 Oe at an optimum PtMn/Co/Ru/Co thickness combination for either PtMn on top or at the bottom. The Hex of PtMn/Co/Ru/Co rapidly increased at the PtMn layer thickness around 10–12 nm and was nearly constant from 12 to 30 nm. It was also found that the saturation field of the Co(3 nm)/Ru(0.8 nm)/Co(2 nm) sandwich, which represents the antiparallel interlayer coupling strength through Ru, remained 2200 Oe even at 300 °C. Thus the combination of the high blocking temperature of 380 °C for PtMn and the large antiparallel exchange interaction of Co/Ru/Co up to 300 °C makes the pinned layer highly stable against various magnetic fields during Joule heating of spin valve sensor stripes. Further, the PtMn synthetic-ferri-pinned-type dual spin valve films showed a large unidirectional exchange field of 2000 Oe and a giant magnetoresistance ratio of 11.0%.

Electrical and Magnetic Properties, and Electronic Structures of Pseudo-Gap-Type Antiferromagnetic <I>L</I>1<SUB>0</SUB>-Type MnPt Alloys

“…Due to such a high stability of antiferromagnetism, especially, MnPt alloy has been investigated intensively from the viewpoint of practical applications as antiferromagnetic pinning layers of giant magnetoresistance (GMR) [11][12][13][14] and tunnel magnetoresistance (TMR) devices. [15][16][17][18] In order to develop the excellent properties for GMR and TMR devices, however, the investigations on fundamental magnetic properties for these practical antiferromagets have been highly desired, because the exchange biasing characteristics are closely related to the spin structures, magnetocrystalline anisotropy energy (MAE) and the magnitude of T N of the antiferromagnetic materials.…”

Paramagnetic to antiferromagnetic phase transformation in sputter deposited Pt–Mn thin films

“…Another material from this class, PtMn, has emerged as a promising candidate for exchange biasing. 8,[15][16][17][18][19] There is a significant processing obstacle that arises in using PtMn as the AFM; the sputter deposited form of PtMn is not antiferromagnetic but is rather a paramagnetic, chemically disordered, face-centered-cubic (A1) phase. A postdeposition anneal is needed to transform PtMn to the desired antiferromagnetic, L1 0 phase.…”

Magnetic recording read head sensor technology

“…While the first commercial spin-valves used an insulating NiO AFM [12], the high pinning strength of ordered metallic PtMn has been the preferred AFM material for a number of years [13]. However, the relatively high critical thickness (about 150 Å) below which the pinning is too weak at the operating temperature is an issue both for pinning and for continued scaling to smaller sensor thickness.…”