Ab initio determination of Kerr angles in Cu₄⁡Ni₈⁢CuₙNi₉/⁢Cu⁡(100) (𝑛=2–10)

Abstract

Calculated polar magneto-optic Kerr rotation and ellipticity angles are presented for the system Cu₄⁡Ni₈⁢CuₙNi₉/⁢Cu⁡(100), n=2,...,10. Contrary to the common belief, the Kerr signals are found to be not directly proportional to the total magnetic moment. It will be shown that in order to assign at least indirectly the size (and sign) of the Kerr angles and therefore the type of coupling to a kind of total magnetic moment, one has to consider weighted layer-resolved moments, e.g., weighted by the damping factors of the reflected waves. As to be expected the occurring oscillations in the Kerr angles with respect to the spacer thickness resemble closely those for the interlayer exchange coupling energy.