Robust evaluation of coercivity in exchange biased films.

Top panel: Inhomogeneity of magnetic field during the sample deposition (a) leads to random fluctuations of the angle between the easy axis and magnetic field during the coercivity measurements (b). Bottom panel: A Stoner-Wohlfarth based approach is applied to estimate the angle and the low-temperature coercivity from the reference values at RT (c). This diminishes the error in measured coercivity, caused by the easy axis direction fluctuations (d). [Display omitted] • Sputtering magnetic field inhomogeneity tilts anisotropy axes in a thin film. • Tilting the axes in respect to field affects coercivity in exchange biased films. • Inclination in 2–3° causes 50% error in measured coercivity H C. • A two-step diagram method is proposed to assess the easy axis H C. • The proposed recalculation diminishes the experimental error in H C. Exact measurement of coercivity in thin magnetic films is of high importance for sensor industry. In exchange biased multilayers, incorporated in magnetoresistive sensors, coercivity of the coupled ferromagnetic layers strongly depends on the orientation of easy axis in respect to field. We show, that in NiFe/IrMn films with high H B /H C ratio, field misalignment ∼2° results in ∼50 % change in coercivity. Inhomogeneous magnetic field in a film deposition device as well as manual installation of the sample in magnetometers result in large error in coercivity. In this work, we propose measurement and analysis protocol to avoid this uncertainty and to evaluate easy axis coercivity values from tilted angle measurements in a wide temperature range using just one reference value of easy axis coercive field, measured at room temperature. [ABSTRACT FROM AUTHOR]