Influence of Cr2O3 thickness on the magnetic properties of NiFe/Cr2O3 bilayers deposited on SrTiO3 single-crystalline substrate

The exchange-coupled bilayers containing antiferromagnetic (AF) Cr2O3 have potential applications in novel spintronic devices with magneto-electric properties. The microstructures and magnetic properties of ion-beam sputtered NiFe/Cr2O3 bilayers are comparatively investigated at different Cr2O3 thicknesses on single-crystalline SrTiO3 (STO) (001) and amorphous SiO2 substrates. The formation of Cr2O3 is verified by X-ray photoelectron spectrometry. X-ray diffraction reveals a distinction in the preferred orientation of Cr2O3 deposited on different substrates. The variations in microstructure are responsible for the higher exchange bias, larger coercivity, and higher temperature stability of magnetization for samples grown on STO substrates. The coercivity and exchange bias at 10 K increases with Cr2O3 thickness. Higher Cr2O3 thickness also results in higher surface roughness, higher irreversibility temperature, and increased peak temperature of the out-of-phase AC susceptibility. This work has revealed the thickness dependence of the microstructure and magnetic properties of NiFe/Cr2O3 bilayers prepared on STO substrate. The outcome of this work may provide some insight for developing novel spintronic devices containing Cr2O3 and perovskite oxides.