Growth And Electrical Control Of Antiferromagnetic FeRh Film

FeRh,as one of the antiferromagnetic materials,plays a crucial role in thermally assisted magnetic recording(TAR)with its special phase transition from antiferromagnet(AF)to ferromagnet(FM).Meanwhile,electrical control of antiferromagnetism is expected to provide a promising avenue for the next generation memories with a combination of high density and low power consumption since the damping factor of antiferromagnetic materials is low.This dissertation investigates the influence of film composition on the transition temperature of FeRh films systematically and optimizes the fabrication of FeRh ultrathin film.Furthermore,the reversible control of FeRh phase transition by electric field is achieved,which might pave the way for non-volatile memories with low power consumption.Firstly,we investigate the influence of film composition,tuned by argon growth pressure and palladium doping,on antiferromagnetic to ferromagnetic transition temperatures of FeRh films.Lower argon pressure and a suitable palladium doping are found to effectively decrease the transition temperature by increasing the Fe atom ratio.In addition,the research indicates that the increase of argon pressure and the annealing procedure are helpful to improve the growth quality,which provides an opportunity to deposit ultrathin FeRh films(5 nm)with a clear phase transition.After that,we investigate the electrical manipulation of the phase transition in ultrathin FeRh films through a combination of ionic liquid and oxide gating.The formation of electric double layer associated with a large electric field induces the migration of oxygen ions between the oxide gate and the FeRh layer,producing the variation of Fe moments in antiferromagnetic FeRh accompanied by the modulation of the transition temperature.Such an electrical control of FeRh phase transition is reversible,which promotes the application of FeRh in the development of antiferromagnetic spintronics devices with low power consumption.