Perpendicular Magnetic Anisotropy And Electrical Transport Properties Of CoHf Multilayers

Good thermal stability,high storage density and low critical current density of magnetisation reversal are the characteristics of perpendicular magnetic recording.Therefore,in high-density storage devices,perpendicular magnetic anisotropy（PMA）films are widely used.The PMA and AHE of ferromagnetic materials have potential physical significance and practical applications,and have also attracted great interest Different from the traditional magnetic storage,the Hall balance,which produces multi-configuration magnetic storage,is a magnetic configuration structure designed and developed based on the AHE of perpendicular magnetic multilayers.This new electronic material manufactured by Hall balance will greatly expand the unit storage density in magnetic storage devices.The magnetic anisotropy of CoHf alloy is large,and the heavy metal Hf can further improve the PMA characteristics,but there are few studies on CoHf.In this paper,the CoHf ferromagnetic layer is selected as the research object.Firstly,Ta/[CoHf（t nm）Pd]₃/Pd multilayer film（t:ferromagnetic layer thickness）is grown on Si/SiO₂ substrate by DC magnetron sputtering.The thickness of the ferromagnetic layer and the annealing temperature are controlled to obtain the sample with perpendicular magnetic anisotropy in order to study the transformation of the magnetic anisotropy.Then.Ta/[CoHf（t nm）/Pd]_n/Ta/[CoHf（t nm）/Pd]_n/Pd samples is grown on this basis,with Ta as buffer layer or isolation layer and Pd as protective layer.Film structure ferromagnetic layer thickness and annealing temperature have been varied to study PMA characteristics and electrical transport properties and to obtain a Hall balance structure.The main conclusions are as follows:1.Themagnetic properties of Ta/[CoHf（t nm）/Pd]₃/Pd multilayer cyclic structure films show that the rectangularity Mr/Ms of Ta/[CoH（1.5 nm）/Pd]₃/Pd film annealed at 300℃ is 0.99,and K_eff is 1.39×10⁶ erg·cm^-3 meaning that it has the best PMA.The study of anomalous Hall effect shows that,regardless of the annealing temperature,the most significant contribution to the anomalous Hall is the phonon scattering in the oblique scattering mechanism,which is followed by the impurity scattcring,the intrinsic mechanism and the edge-hopping scattering mechanism have little in fluence on the AHE of the sample,and the anomalous Hall resistance ρ_AH first rises and then drops with the enhancement of the annealing temperature2.The magnetic properties of Ta/[CoHf（t nm）/Pd]_nTa/[CoHf（t nm）/Pd]_n/Pd multilayer cyclic structure films were studied.It was found that through the design of the film structure,it is easier to obtain a Hall balance structure with high HRR（Hall resistance ratio）in the Ta/[CoHf(0.5nm/Pd]₃/Ta/[CoHf（0.5 nm）/Pd]₄/Pd structure.Then the anomalous Hall Effect is studied,and four different Hall resistance states are observed,the HRR is small,and the Hall balance is not obtained.However,the Ta/]CoHf（0.5 nm）/Pd]₃/Ta/[CoHf（0.5 nm）/Pd]₄/Pd film anncaled twice（350℃+200℃）realized the Hall balance structure at 100 K,and the HRR was as high as 1248342%.In this paper,the preparation of Collf multilayer Hall balance is realized,which will contribule to the research and development of spintronics devices.The new high-density 3D storage mode provides an effective way for the design of magnetic storage materials and devices,and provides a potential innovation direction for its subsequent development.