Study On Magnetic Properties Of MnGa Films Deposited By Magnetron Sputtering

Recently, MnGa film is an emerging candidate for the futural high-density magnetic recording media and spin-transfer torque magnetic random access memory(STT-MRAM)due to its intrinsic magnetic characteristics such as large perpendicular magnetic anisotropy(PMA), high spin polarization(P), lowdamping coefficient(?), flexible saturation magnetization(Ms)and rich source of raw materials andinexpensive cost.In this thesis, MnGa films with theoretical significance and application value are deposited onto MgO(100) substrates by magnetron sputtering and the magnetic parameters,crystal structure,and surface morphology of the sputtered MnGa films are analyzed by vibrating sample magnetometer(VSM), X-ray diffraction(XRD) and atomic force microscope(AFM), respectively. Moreover, the influences of post-annealing temperature( Ta),sputtering Ar pressure and film thickness on the microstructure and magnetic properties of MnGa films were investigated.The research results indicate that(1) Mn content in the sputtered MnGa filmsis higher than that inMnGa alloy target and the Mn content increases with the increasing of sputtering power, but decreases with the increasing of sputtering Ar pressure.(2) The grain size and surface roughness of MnGa films increase gentlyat Ta below 500 and then climb up rapidly at Ta above500. When Ta is 500,MnGa filmsexhibit the best perpendicular magnetic propertiesand low surface roughness.(3) Coercivity and remanence squareratio of MnGa films perpendicular to the film surface decrease with the increases of sputtering pressure and film thickness. As the film thickness is 50 nm, coercivity and remanence squareratioin the out of plane direction are much larger than those of the in-plane direction, showing a good PMA,and the PMA of MnGa films gradually weakens with increase of film thickness.