Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 36: Magnetic Heusler Compounds II

MA 36.1: Invited Talk

Thursday, March 29, 2012, 09:30–10:00, H 1012

Tetragonal Heusler-like alloy films with perpendicular magnetic anisotropy for spin torque applications — •Shigemi Mizukami and Terunobu Miyazaki — WPI-Advanced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, Japan, 980-8577

Some Heusler alloys have half-metallic band structure, exhibiting giant tunnel magnetoresistance (TMR) in magnetic tunnel junctions (MTJs). However, the conventional Heusler alloys, such as Co₂MnSi, have chemically ordered cubic structure, so that these alloys show relatively weak magnetic anisotropy. Magnetic films with a large perpendicular magnetic anisotropy (PMA) are advantageous to the spin torque application, such as magnetic random access memory, because PMA reduces switching current density and increase thermal stability of magnetization directions. Thus, it is interesting to study on Heusler alloy with a large PMA. It has been predicted by the group in Mainz that Heusler-like alloy Mn₃Ga exhibits a large spin polarization as well as a large uniaxial magnetic anisotropy. We have obtained Mn_3−xGa (x=0.5) epitaxial films using a UHV-magnetron sputtering and reported a large uniaxial magnetic anisotropy energy K_u of 12 Merg/cm³ and also low saturation magnetization of 250 emu/cc, so far. In this talk, we will present structural and magnetic properties and a relatively low Gilbert damping observed in a ultrafast precessional dynamics of magnetization for the Mn_3−xGa alloy films. Furthermore, the TMR effects in MgO-MTJs with Mn_3−xGa electrodes will also be discussed.