Temperature-dependent interlayer coupling in Ni/Co perpendicular pseudo-spin-valve structures

Abstract

The temperature-dependent coupling mechanisms in perpendicular pseudo-spin valves based on the following structure, [Ni/Co] 5 /Cu(t Cu )/[Ni/Co] 2 , are investigated. Despite a thick (t Cu 3 nm) Cu spacer, room-temperature measurements reveal complete coupling of the [Ni/Co] 5 and [Ni/Co] 2 multilayers. This coupling can be attributed to strong long range magnetostatic stray fields that penetrate the spacer layer. This results in magnetic domain imprinting and vertically correlated domains throughout the reversal process. Surprisingly, when the temperature is reduced, a complete decoupling is observed. This somewhat counterintuitive result can be explained by a large difference in the [Ni/Co] 5 and [Ni/Co] 2 multilayer coercivities at reduced temperatures, which then impedes domain imprinting and promotes decoupling. Finally, the decoupling temperature is found to increase with spacer thickness.

Magnetic droplet solitons in orthogonal nano-contact spin torque oscillators

“…Owing to their tunable saturation magnetization (MS) and perpendicular magnetic anisotropy (PMA), all magnetic Co/Ni multilayers [26] (MLs) have proven to be the ideal material for use as the OOP FL.…”

Magnetic tunnel junctions using Co/Ni multilayer electrodes with perpendicular magnetic anisotropy

“…The fact that top and bottom layers reverse together is due to dipolar interactions which effectively couples the two layers. 25,26 As a consequence, one has to carefully tune the electrodes not only to insure PMA but also limit the inter-layer dipolar coupling.…”

Pseudo spin valve thin films with crossed magnetic anisotropies

“…Further possible applications include magnetoresistive random access memories based on the spin transfer torque effect [3][4][5][6], which can be combined with pseudo spin valve (PSV) systems. Of particular interest are PSV based sensors, consisting of magnetic films with perpendicular magnetic anisotropy (PMA), which have mainly been based on [Co/Ni] [7,8], [Co/Pd] [9][10][11], and [Co/Pt] [12,13] multilayered systems. However, due to the large hysteresis observed in these PSV thin films, they are not particularly suitable for field sensing applications.…”