Magneto-optical Kerr effect in perpendicularly magnetized (Co2Pt6)n/Pt(111) superstructures

Perpendicular magnetism facilitates an increase of the storage density by a factor 2-8 as compared to longitudinal recording. Besides the improved chemical and physical stability of Co/Pt superstructures compared to RE-TM alloys, a perpendicular easy axis can be obtained by selecting a suitable Co/Pt bilayer thickness ratio. For different repetition numbers n <= 6 ab initio calculated Kerr angles are presented for (Co2Pt6)(n) superstructures on Pt(111) with a 6 Pt layers thick cap in a photon energy range of 1-8 eV. The calculated maximum in the Kerr rotation angle occurs at an energy close to the experimentally observed value. Assuming an exponential decay of the gradient of theta(K) with respect to n, an extrapolation of the calculated data to large n was performed in order to compare the obtained results to available experimental data.