R Misra, T Ha, Y Kadmon, Cedric J. Powell, Mark D. Stiles, Robert McMichael
We have investigated the surface roughness and the grain size in giant magnetoresistance (GMR) spin valve multilayers of the general type: FeMn/Ni80Fe20/Co/Cu/Co/Ni80 Fe20 on glass and aluminum oxide substrates by scannin tunneling microscopy (STM). The two substrates give very similar results. These polycrystalline GMR multilayers have a tendency to exhibit larger grain size and increased roughness with increasing thickness of the metal layers. Samples deposited at a low substrate temperature (150K) exhibit smaller grains and less roughness. Valleys between the dome-shaped individual grainsare the dominant form of roughness. This roughness contributes to the ferromagnetic, magnetostatic coupling in these films, an effect termed " orange peel" coupling by Neacute}el. We have calculated the strength of this coupling, based on our STM images, and obtain values generally within about 20% of the experimental values. It appears likely that the ferromagnetic coupling generally attributed to so-called "pinholes" in the Cu when the Cu film thickness is too small is actually "orange peel" coupling caused by these valleys.
, Ha, T.
, Kadmon, Y.
, Powell, C.
, Stiles, M.
and McMichael, R.
STM Studies of GMR Spin Valves, Materials Research Society Symposium Proceeding, San Francisco, CA, US, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=620459
(Accessed December 8, 2023)