Exchange bias in thin-film (Co/Pt)3/Cr2O3 multilayers

We have fabricated exchange-biased Co/Pt layers ((0.3 nm/1.5 nm) 3) on (0 01)-oriented Cr2O3 thin films. The multilayered films showed extremely smooth surfaces and interfaces with root mean square roughness of E0.3 nm for 10mm 10mm area. The Cr2O3 films display sufficient insulation with a relative low leakage current (1.17 10 A/cm at 380MV/m) at room temperature which allowed us to apply electric field as high as 77MV/m. We find that the sign of the exchange bias and the shape of the hysteresis loops of the out-of-plane magnetized Co/Pt layers can be delicately controlled by adjusting the magnetic field cooling process through the Néel temperature of Cr2O3. No clear evidence of the effect of electric field and the electric field cooling was detected on the exchange bias for fields as high as 77MV/m. We place the upper bound of the shift in exchange bias field due to electric field cooling to