Study On Exchange Bias Effect Of Y₃Fe₅O₁₂/BiTi_0.05Fe_0.95O₃ Heterojunction

In recent years,in order to meet the requirements of the development of high-speed and low-power computing and storage technology in the post-Moore era,people turn their attention to spin wave devices and put forward the magnetic insulator/non-magnetic metal/magnetic insulator magnet valve structure in 2018.Then,we propose a room temperature electronically controlled magneton valve structure and a non-volatile memory device,which is based on the magneto valve structure to realize the change of magnetic moment rotation and magnetoresistance in the electric field control device,and realize the electronically controlled magnetic storage function,which can further reduce the power consumption of the device.This paper focuses on the study of the multi-iron exchange bias heterojunction structure in the device structure,including the preparation,generation mechanism and exchange bias effect of the heterojunction materials.In this paper,ferrite material Y₃Fe₅O₁₂ is used as ferromagnetic layer(FM),Ti doped BiFe O₃ as antiferromagnetic layer(AFM)to form Y₃Fe₅O₁₂/BiTi_0.05Fe_0.95O₃heterojunction to study the exchange bias effect.In this paper,the preparation of Y₃Fe₅O₁₂ thin films on Sisubstrates was investigated by magnetron sputtering.The thin films were prepared under different sputtering power,sputtering pressure and annealing temperature.The films prepared at 100W sputtering power and 3Pa pressure and heat treatment at 750?for 3h have good crystallinity,root mean square roughness of0.936nm and saturation magnetization of 136emu/cm³.In this paper,BiFe O₃ thin films with good crystallinity and no impurity phases were prepared on Pt/Ti/SiO₂/Sisubstrates by sol-gel method.In order to further optimize the ferroelectric properties of BiFe O₃ thin films,the Ti element is used to doping the BiFe O₃ film in the proportion of 0-5%.When the doping ratio of Ti was 5%,the saturation polarization Ps of the thin films was 40.9?C/cm²,which was about twice that of pure BiFe O₃ thin films,and the leakage current was 2.9×10^-4A/cm²,which was36%lower than that of pure BiFe O₃ thin films.In this paper,Y₃Fe₅O₁₂/BiTi_0.05Fe_0.95O₃ heterostructures are prepared on the basis of the above,and the magnetic hysteresis loops of the heterostructures are measured at different temperatures.It is observed that the heterostructure has obvious exchange bias effect at 3K.The exchange bias field H_EB is-53.3Oe and the coercivity H_C is655.5Oe.By fitting H_EB and H_C at different temperatures,it is found that H_EB and H_Cshow an exponential decay trend with the increase of temperature.By measuring the field cooling and zero field cooling of the heterojunction system under different fields,it is proved that the heterojunction system has spin glass effect.The relationship between the irreversible magnetization temperature Tirr in the glass state and the external magnetic field H is fitted.It is found that there is a linear relationship between the irreversible magnetization temperature and the external magnetic field H^2/3.