MAGNETORESISTANCE IN NI80FE20 CU/NI80FE20/FE50MN50 SPIN VALVES WITH LOW COERCIVITY AND ULTRAHIGH SENSITIVITY/

We present magnetoresistance measurements on Ni80Fe20/Cu/Ni80Fe20/Fe50 Mn50 spin valves with crossed anisotropies: the easy magnetization dir ection of the unbiased Ni80Fe20 layer is perpendicular to the exchange biasing field which effectively works on the second Ni80Fe20 layer du e to the interaction with the Fe50Mn50 layer. The hysteresis in the lo w-field magnetoresistance is less than 0.03 kA/m, which is ten times s maller than the hysteresis for similar materials with parallel anisotr opies. The sensitivity (partial derivative R/R(infinity))/partial deri vative H ranges from 8% to 18%/(kA/m), depending on the preparational method. To our knowledge this combination of very high sensitivity and very low coercivity has not been reported before.