Magnetooptical Spectroscopy Of Ga+ Irradiated Pt/Co/Pt Sandwiches

The magnetic properties of ultrathin Pt/Co/Pt sandwiches depend on the interface structure and can thus be controlled by ion irradiation [1]. In the present work, we study the magneto-optic properties by polar Kerr rotation upon Ga+ irradiation of Pt(3.5 nm)/Co(2.6 nm) /Pt(4.5 nm) trilayers which have been sputter deposited on (001) Al2O3 substrates. In Figure 1 the MO spectra at saturation before and after irradiation are compared. The enhanced MO amplitude after irradiation results from an increased thickness of the alloyed PtxCo1-x interface layer [2]. The MO spectra were modeled assuming interface PtxCo1-x layers with a monotonous x gradient using the data of ref. [3]. The curves in Fig. 1 were obtained assuming the structure shown in Fig. 2, i.e., Pt(2.8 nm)/ PtxCo1-x(1.1 nm)/Co(2.3 nm) /PtxCo1-x(1.1 nm)/Pt(4.0 nm) and Pt(1.2 nm)/ PtxCo1-x(4.0 nm)/ Co(1.0 nm)/PtxCo1-x(3.0 nm) /Pt(1.5 nm)/Al2O3 for the non-irradiated sample and the sample irradiated with a dose of 1014 Ga+/cm², respectively. The changes in the MO spectra after irradiation confirm the expected high sensitivity of the coupled 3d levels of Co and 5d levels of Pt (with high spin-orbit interaction) to the interface geometry [2]. Partially supported by NSF (DMR 0605629 and DMR 0907053), Research Corporation (CC6471), CU-NIST Joint Project and by Ministry of Education, Youth and Sport of the Czech Republic (MSM 6198910016, 0021520834 and ME09045), Grant Agency of Charles University (3146/2008), Czech Science Foundation (P204/10/P346), EU-“Research Infra-structures Transnational Access” program “Center for Appli-cation of Ion Beams in Materials Research” (025646) and DAAD.
[1] J. Jaworowicz et al., Appl. Phys. Lett. 95, 022502 (2009)
[2] D. Weller et al. J. Magn. Magn. Mat. 93, 183 (1991)
[3] S. Visnovsky et al., IEEE Trans Magn. 29, 3390 (1993)