Since the exchange bias(EB)effect was discovered in the Co/CoO core-shell nanoparticles,it has been extensively studied in various ferromagnet(FM)/antiferromagnet(AFM)bilayers due to its crucial role in spintronics devices.In this article,we review the investigation of the EB in our research group.First,we outline basic features of the EB,including the effects of the constituent layer thickness,the microstructure and magnetization of the FM layers,and we also discuss asymmetric magnetization reversal process in wedged-FM/AFM bilayers.Secondly,we discuss the mechanisms of the positive EB and the perpendicular EB.Thirdly,we demonstrate the hysteretic behavior of the angular dependence of the EB and analyze the EB training effect.Finally,we discuss the roles of the rotatable anisotropy in the two phenomena.
We prepare Si x (ZrO 2 ) 100 x composite films using the co-sputtering method. The chemical structures of the films which are prepared under different conditions are analyzed with X-ray photoemission spectroscopy. Thermal treatment influences on optical property and resistance switching characteristics of these composite films are investigated by spectroscopic ellipsometry and semiconductor parameter ana- lyzer, respectively. With the proper Si-doped Si x (ZrO 2 ) 100 x interlayer, the Al/ Si x (ZrO 2) 100 x /Al device cell samples present very reliable and reproducible switching behaviors. It provides a feasible solution for easy multilevel storage and better fault tolerance in nonvolatile memory application.
Interfacial magnetic anisotropy in a Pt/Co1-xFex /Pt multilayer is tuned by doping iron atoms into the cobalt layer.The perpendicular magnetic anisotropy and out-of-plane coercivity are found to decrease with increasing x.For a specific x,the out-of-plane coercivity acquires a maximal value as a function of the thickness of the CoFe layer.At low temperature,the coercivity is enhanced.Small coercivity but reasonably large perpendicular magnetic anisotropy can be obtained by controlling the x and CoFe layer thickness.
The mechanism of ferromagnetic ordering in ZrO_x film is investigated by both experimental observation and theoretical calculation.Magnetic measurements reveal that the magnetic properties can be adjusted from diamagnetism to ferromagnetism by varying the oxygen stoichiometry.We find that oxygen-rich defects can be responsible for the observed magnetic properties by taking the measurements of x-ray photoelectron spectroscopy and room temperature photoluminescence spectra.Density functional theory calculations further confirm that the ferromagnetic order is mainly driven by the exchange interaction between the oxygen antisites and the neighboring anion atoms.
