High coercivity in large exchange-bias Co/CoO-MgO nano-granular films*
Ge Chuan-Nana),b), Wan Xian-Ganga)†, Eric Pellegrinc), Hu Zhi-Weid), Wen-I Liange), Michael Brunsf), Zou Wen-Qina), Du You-Weia)
       
Magnetic hysteresis loops of (a) the Co56/(CoO)32-(MgO)12 sample and (b) the Co75/(CoO)15-(MgO)10 sample. All data were taken by warming up after cooling down to 2 K in a 2 kOe field. The inserts show the details of the hysteresis loops. (c) Exchange bias H E as a function of temperature for the Co56/(CoO)32-(MgO)12 sample and the Co75/(CoO)15-(MgO)10 sample. (d) Magnetic coercive field H C as a function of temperature for the Co56/(CoO)32-(MgO)12 sample and the Co75/(CoO)15-(MgO)10 sample.