Epitaxial PtMn∕NiFe exchange-biased bilayers containing directly deposited ordered PtMn

Abstract

Pt Mn ∕ Ni Fe exchange-biased bilayers have been grown epitaxially on Si (001) using molecular-beam epitaxy. Spontaneous formation of the chemically ordered face-centered-tetragonal phase of PtMn layer was confirmed without postgrowth magnetic-field annealing, whose Néel axis is perpendicular to the PtMn∕NiFe interface. The exchange anisotropy field stabilizes above a PtMn thickness of 15nm which is much lower than that for polycrystalline PtMn-based exchange-biased systems. For comparison, PtMn∕NiFe exchange-biased bilayers have been prepared epitaxially on MgO (001) substrate. Spontaneous formation of the chemically ordered PtMn layer was also confirmed with Néel axis parallel to the PtMn∕NiFe interface. The exchange anisotropy field of the bilayer on MgO stabilizes beyond a PtMn thickness of 15nm as well.

Effect of grain size on magnetic properties and microstructure of Ni80Fe20 thin films

“…It can be used as a pinned ferromagnetic layer in an FM/antiferromagnetic (AFM) exchange-biasing system, including NiFe/IrMn, NiFe/NiO, and NiFe/PtMn systems [4][5][6]. In particular, an NiFe thin film can be inserted to a pinned or free layer of magnetic tunnel junctions (MTJs) in magnetoresistance random access memory (MRAM) and recording-head applications [7,8]. It can also generate high tunneling magnetoresistance (TMR) at room temperature (RT) in CoFeB/MgO/NiFe and NiFe/AlO x / CoFe MTJs [9,10].…”