Hysteretic magnetisation curves in the granular Cu100-xCox system

The magnetic hysteresis properties of granular Cu_100-xCo_x alloys (x = 5 to 20) containing nanometric Co particles, prepared under different quenching conditions and submitted to various anneals, have been measured at room temperature. Major loops (vertex field 1 × 10⁴ Oe) and minor loops (vertex field between 1 × 10² and 9 × 10³ Oe) were measured by vibrating-sample magnetometry. The features of major loops were analysed in terms of sample composition and structural state; the dependence of remanence and coercivity of minor loops on vertex field has been analysed in detail. A novel graphical representation method, particularly suitable for describing the details of the narrow hysteresis loops observed in granular systems has been proposed and checked.