The Reseach Of Preparation,Magnetic And Electrical Properties For Ordered FePt_1-xRh_x Alloy Films

With the rapid development of the information age,the data is growing exponentially day by day.With the increase of storage density of hard disk,perpendicular magnetic recording technology has successfully replaced in-plane magnetic recording technology in order to overcome the superparamagnetic limit.Various theoretical and experimental studies on perpendicular magnetic recording have played an active role in the development of perpendicular magnetic recording.This paper introduces a kind of multilayer composite films based on FePt alloy and FePt_0.5Rh_0.5 alloy.It is expected to be used on magnetoresistance?MR?devices for improving the magnetoresistive heads.In this paper,FePt single layer films,FeRh single layer films,Fe₂Pt_1-xRh_x single layer films and FePt/FePt_0.5Rh_0.5 bilayer films were prepared by magnetron sputtering on MgO?001?single crystal substrate.The magnetic and electrical transport properties of them were studied.And the main results are as follows:?1?FePt single layer films were grown at different substrate temperatures using Pt and Cr/Pt alloy as buffer layers respectively.The effects of film thickness and degree of order on magnetic properties were investigated.The results show that the the structure of FePt films transform gradually from A1 disordered phase to L1₀ ordered phase with the increase of substrate temperature.L1₀ ordered FePt films with a?001?orientation have perpendicular magnetic anisotropy and the easy axis are in the perpendicular direction.The coercivity of 45 nm FePt thin films in perpendicular direction is 4.7 kOe.And the coercivity decreases gradually with the increase of film thickness.The coercivity in perpendicular direction is 0.74 kOe when the thickness of FePt films is 135 nm.?2?FeRh single layer films were grown at different substrate temperatures and annealing temperatures using Pt as buffer layer.The effects of substrate temperature and annealing temperature on the order degree and magnetic property of FeRh films were investigated.The results show that the B2 phase FeRh films with good quality can be obtained by growing at 600?and annealing in situ at 700?.B2 ordered FeRh films are antiferromagnetic?AFM?at room temperature,and heating can make them transform to ferromagnetic?FM?phase.The phase transition temperature can be adjusted between360-400 K by changing substrate temperature and annealing temperature.And there is a marked drop in resistivity between the two magnetic phases.We find that FeRh is also an antiferromagnetic material with anisotropic magnetoresistance effect.?3?FePt_1-xRh_x single layer and FePt/FePt_0.5Rh_0.5 bilayer films were grown at different substrate temperatures using Pt as buffer layer.The FePt1-xRhx single layer films?0?x?0.5?grown at 700?are L1₀ ordered phase.FePt_0.5Rh_0.5 films are antiferromagnetic at room temperature,and there are two antiferromagnetic arrangements below room temperature:?1/2 1/2 1/2?and?0 0 1/2?.The transition temperature between the two antiferromagnetic phases is about 276K.FePt/FePt_0.5Rh_0.5 bilayer films with good quality can be obtained by growing FePt on Pt buffer at 700?first and then growing FePt_0.5Rh_0.5 on FePt layer at 600?.They are FM-AFM heterostructures,and the exchange bias field of bilayer films decrease with the increase of temperature.The higher order degree of AFM layer is obtained,the larger exchange bias field at low temperature will be led.