title: Enhanced exchange bias and coercivity arising from heterojunctions in Ni-NiO nanocomposites.
abstract: By a reflux process, we prepared Ni-NiO nanocomposites that are face-centered cubic (fcc). By tuning the precursor concentration, we controlled the Ni content in the Ni-NiO nanocomposites. We found that both the interface of Ni and NiO crystal lattices and the weight fraction of Ni have significant impacts on their magnetic properties. There is increase of saturation magnetization and decrease of coercivity (HC) with the increase of the Ni weight fraction. Large exchange bias (HE) and enhanced HC are observed at 5 K, which are due to the creation of heterojunctions at the interfaces of ferromagnetic Ni and antiferromagnetic NiO. After optimization, it is observed that the Ni-NiO nanocomposites with an Ni content of 2.6% show an HC and HE of 1068 and 350 Oe, respectively.
authors.affiliation: National Laboratory of Solid State Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China. wzhong@nju.edu.cn.
authors.forename: Xiu-Juan
authors.initials: XJ
authors.lastname: Yao
authors.forename: Xue-Min
authors.initials: XM
authors.lastname: He
authors.forename: Xue-Yin
authors.initials: XY
authors.lastname: Song
authors.forename: Qian
authors.initials: Q
authors.lastname: Ding
authors.forename: Zhi-Wen
authors.initials: ZW
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Zhong
authors.forename: Chak-Tong
authors.initials: CT
authors.lastname: Au
authors.forename: You-Wei
authors.initials: YW
authors.lastname: Du