ИСТИНА

The cobalt-carbon multilayers are of a great practical interest, especially for soft X-ray range [1] as well as for novel applications [2]. Recently the important role of surface intermixing in ultrathin Co/C films and of Co-layer thickness was shown [3]. The magnetic properties of C/Co/C/Co/C multilayers (MLs) with various C and Co layers thickness have been studied by TKE spectrometry, SQUID and VSM magnetometry at 80 300 K. The MLs have been sputtered with DC magnetron, the thickness of Co layers was varied from 4 to 40 nm, and thickness of middle C layer was varied in the range 0.5 15 nm. The crucial role of C and Co layers thickness was revealed both for magnetic as well as for structural properties of MLs. TEM, X-ray diffraction, and in-situ resistivity measurements revealed the metal layer being an amorphous cobalt-carbon alloy as a result of the layer intermixing for Co thickness < 5 nm. An avalanche crystallization of the amorphous alloy took place and monocrystalline hcp Co layers were formed for Co thickness > 5 nm. Magnetic and magneto-optical properties of MLs have been studied in as-deposited state and after one hour annealing below crystallization temperature (250 °C). The one order increase of the coercivity has been found for annealed samples in comparison with as deposited films. The TKE spectra of the samples with Co thickness less than 5 nm have been found to be similar to the polycrystalline Co spectrum. Magnetic interaction between Co layers separated by amorphous carbon of different thickness is discussed.