We report second-harmonic magneto-optic Kerr effect investigations of magnetic heterostructures. The heterostructures studied are multilayers of Si/Al2O3/Cu(50 nm)/Ni81,Fe19(x), Si/Al2O3/Cu(50 nm)/Co(2 nm)/Ni81Fe19(x), and Si/Al2O3Cu(50 nm)/Ni81,Fe19(x)/Cu(5 nm), where x ranges from 1 to 30 nm. For films thinner than the optical penetration depth, the transverse second-harmonic Kerr effect experimentally separates and distinctly identifies each of these multilayered structures. We find that the addition of the 2 nm Co layer between Cu and Ni81Fe19 increases the magnetic signature in the second-harmonic intensity by more than a factor of two. This increase correlates with the observed magnetoresistance increase in spin valves with the addition of Co. For films thicker than the penetration depth, the structures with air-exposed Ni81Fe19 are identical, but they differ significantly from Ni81Fe19 films capped with Cu. We used spectroscopic ellipsometry to determine the linear optical properties of each film in the structure. Modeling of both Cu(50 nm)/Ni81Fe19 and Cu(50 nm)/Ni81Fe19(x)/Cu(5 nm) suggests that the buried magnetic interfaces are better generators of second-harmonic than the air-exposed Ni81Fe19 surface. There is a distinct decay in the magnetic component of the second-harmonic intensity for film thicknesses below 2 nm.
ASJC Scopus subject areas
- Physics and Astronomy(all)