Anhysteretic magnetization reversal of spin valves with a strong and weak interlayer coupling

The hysteresis of magnetoresistance has been studied as a function of the angle between the magnetic field applied in the plane of layers and the easy axis for spin valves with the composition Ta, (Ni₈₀Fe₂₀)₆₀Cr₄₀] /Ni₈₀Fe₂₀/Co₉₀Fe₁₀/Cu/Co₉₀Fe₁₀/Mn₇₅Ir₂₅/Ta. In spin valves with a strong interlayer coupling at a small deviation of the magnetic-field direction from the easy axis there was revealed a sharp (to a few tenths of an oersted) narrowing of the hysteresis loop of the magnetization reversal of the free layer. Based on an analysis of the angular dependences of the hysteresis, critical angles at which a change occurs in the mode of the magnetization reversal have been determined. In terms of the Stoner-Wohlfarth model of the coherent rotation of the magnetization, the angles at which a transition to an anhysteretic magnetization reversal is observed have been estimated theoretically for the spin valves with a strong interlayer coupling.