Magnetization reversal and field annealing effects in perpendicular exchange-biased Co∕Pt multilayers and spin valves with perpendicular magnetization

Abstract

Magnetization reversal asymmetry in [Co/Pt]/CoFe/IrMn multilayers with enhanced perpendicular exchange bias J. Appl. Phys. 113, 033901 (2013); 10.1063/1.4775837 Asymmetric magnetic reversal of perpendicular exchange biased ( Co ∕ Pt ) 5 ∕ Ir Mn probed by magnetoresistance and magnetic force microscopy Reduction in critical current of current-induced switching in exchange-biased spin valves J. Appl. Phys. 97, 10C712 (2005); 10.1063/1.1853279 Correlation between perpendicular exchange bias and magnetic anisotropy in IrMn ∕ [ Co ∕ Pt ] n and [ Pt ∕ Co ] n ∕ IrMn multilayersA study on the Co layer thickness dependence of the magnetization reversal process and magnetoresistance of perpendicular exchange-biased Co/ Pt multilayers and spin valves with perpendicular magnetization is presented. The hysteresis of ͓20 Å Pt/ t Å Co͔ 3 / 100 Å IrMn/ 20 Å Pt multilayers with t ജ 5 Å are found to be asymmetric after deposition. This asymmetry reflects a lateral variation in the perpendicular exchange-bias direction due to the growth of IrMn onto multidomain Co/ Pt multilayers. Magnetic annealing in a perpendicular field removes the switching asymmetry and leads to a maximum exchange-bias field of 16.3 mT for t = 7 Å. Perpendicular spin valves with an optimized structure of 50 Ta/ 20 Å Pt/ t Å Co/30 Å Cu/t Å Co/20 Å Pt/6 Å Co/ 3 Å Pt/100 IrMn/ 20 Å Pt are found to exhibit good switching behavior but limited magnetoresistance for small Co layer thickness. The magnetoresistance of these spin valves increases with t up to a maximum of 3.9% for t = 10 Å, beyond which it decreases due to simultaneous magnetization reversal in the ferromagnetic layers. Magnetic field annealing of these top-pinned structures reduces the exchange-bias field and the magnetoresistance.

Magnetization reversal in exchange biased nanocap arrays

“…The IrMn layer was used as AF to induce EB in the Pt/Co multilayers [25][26][27][28]. Since the top Co layer is polycrystalline, the IrMn is also polycrystalline and will exhibit AF domains with in-plane and out-of-plane spin configurations.…”

Magnetic reversal phenomena in pseudo-spin-valve films with perpendicular anisotropy

“…Most perpendicular spinvalve systems reported consist of superlattice structures such as Co/ Pt laminates with upwards of 15 individual layers. [1][2][3][4] Magnetic reversal mechanisms have been well studied in single-layer films with perpendicular anisotropy 5,6 but there are few reports of reversal in spin-valve structures. In this paper we describe magnetization reversal in a simple spinvalve system of the form Ti/ CoCrPt/ Ti/ CoCrPt with perpendicular anisotropy.…”

Evidence for asymmetric rotation of spins in antiferromagnetic exchange-spring

“…Figure 1(a) shows the magnetoresistance curve of the junction at vertical H, where a hysteresis window with a stable high-resistance state (HRS) at +H and low-resistance state (LRS) at −H indicates a partial rotation of FeMn moments from in-plane [right inset of figure 1(a)] to out-of-plane (left inset) direction [6]. This observed asymmetry between the two states (HRS/LRS) is induced by the downward component of interfacial FeMn spins, which is an imprint of the domain pattern of as-deposited Co/Pt [6,23,24]. To be specific, the magnetic flux leakage from magnetron guns is able to make downward spins favorable in as-deposited Co/Pt, which is confirmed by its remanence.…”