Pt capping effects on the perpendicular magnetic properties of Pt/Co2MnSi/MgAl2O4 trilayers

A series of Pt/Co2MnSi(CMS)/MgAl2O4(MAO) trilayers are fabricated by sputtering. Perpendicular magnetic anisotropy (PMA) is observed to build in the Pt/CMS/MAO trilayers annealed at 200 degrees C with a relatively narrow range of CMS thickness from 2 to 2.5 nm. An interfacial anisotropy energy density of 0.40 +/- 0.04 erg/cm(2) is obtained in the trilayers. Significantly enhanced PMA is demonstrated in the trilayers capped with Pt. PMA is shown to be demonstrated in a wide window of annealing temperature ranged from 200 to 400 degrees C with CMS thickness increases from 2 to 3.5 nm. The maximum effective perpendicular anisotropy is determined to be in the order of 10(6) erg/cm(3). A large interfacial perpendicular anisotropy energy density of 1.95 +/- 0.15 erg/cm(2) is achieved for Pt-caped trilayers annealed at 300 degrees C. Strong Pt (111) peak is observed in the presence of the Pt capping, which may be responsible for the significantly enhanced PMA. For the Pt-capped trilayers pronounced effect of MAO thickness on PMA is observed. MAO is found to be requisite in developing PMA. For the structure with thick MAO high temperature annealing is required to promote PMA. Our findings are useful for fabricating perpendicular spintronic devices that require high PMA and high annealing stability.