On the structure and magnetism of Ni/Si and Fe/Si bilayers irradiated with 350-MeV Au ions

Behavior of crystalline silicon under huge electronic excitations: A transient thermal spike description

“…Evidence for atomic mixing induced by electronic energy deposition in metallic layers deposited on Si has been reported by Leguay [36]. Although, Sinha et al [37] come to the conclusion that metallic layers do not mix with the Si crystalline substrate, recent experimental work shows the contrary [38][39][40][41]. For example Sisodia et al [38] suggest that irradiation with swift heavy ions causes some mixing at interface of Ti/Si that could be expected as in the case of Ti/Ni [36] since one of the materials is sensitive to swift heavy ions.…”

“…Mixing appears even for Ni deposited on Si which is rather unexpected since the two materials are, to our knowledge, insensitive to monoatomic ion irradiation. Indeed, a high mixing rate was found for Ni layers on Si irradiated by 350 MeV Au 26+ [39][40][41], being several times larger than that for irradiation by 400 keV Au in the nuclear collision regime. Moreover the threshold of mixing was determined by Kraft et al [41] in the following range of energy loss, 9-16 (28-47) keV/nm for Si (Ni), respectively, being easily attained with swift heavy ions.…”

“…This interpretation is supported by the value of the estimated effective diffusion coefficients which are comparable with those for interdiffusion D in a liquid rather than those for solid state diffusion. From the formula given by Kraft 2Dt s ¼ k=pr 2 t , where the coefficient k is the mixing coefficient as defined by Kraft et al [41], r t corresponds to a radius of the melting zone and t s the duration of melting, the value of the D coefficient was evaluated for Ni/Si irradiated by Au and Xe [39,41] and is $10 À3 cm 2 /s. Such a value is in agreement with that extracted by Srivastava et al [48] and also with that corresponding to impurity diffusion in molten silicon [64] excited by a ns laser pulse.…”

Magnetic patterning by means of ion irradiation and implantation

“…A modification of the magnetic texturing and thereby of the magnetic anisotropy by means of ion irradiation is investigated using high energy heavy ion irradiation [95][96][97]. These energies are usually not compatible with local patterning approaches.…”

Xenon-ion irradiation of Co/Si bilayers: Effects of interface structure and ion energy

“…Nonetheless, the correlations existing between the microstructural properties of ion-irradiated or ionmixed metal/silicon bilayers and their magnetic properties (in the case of 3d elements) is far from being understood. Moreover, recent mixing experiments in the Fe/Si system have given evidence that the structure of the interface and crystallinity of the Si substrate strongly influence the mixing rate [11,12]. Phase transformations in Xe-irradiated Co and Co/Fe films have recently been studied by Zhang and collaborators [13,14].…”