Atomic level mixing induced by Kr irradiation of FeCo∕Cu multilayers

Abstract

The effects of Kr ion irradiation of FexCo1−x∕Cu multilayers are investigated by means of magnetic and x-ray measurements. The irradiation was performed at room temperature with 600keV of Kr, and the fluences were ranged from 1×1015to5×1015ions∕cm2. X-ray diffraction patterns show that the irradiation was able to produce a significant grain growth and, at the same time, it triggered a strain release. The x-ray absorption measurements around Fe K edge have shown that the FeCo environment changed from bcc, for the as-deposited multilayer, to fcc after appropriate fluence, depending on the Cu thickness and on the Fe∕Co content. For 50Å of Cu, the phase transformation occurs even for the lowest fluence, regardless the Fe∕Co concentration. For 25Å of Cu, it depends on the Fe∕Co concentration. After irradiation, the saturation magnetization suffers a strong decrease, especially for 50Å of Cu. The temperature for the onset of irreversibility also decreases with irradiation, again being the effect stronger for 50Å of Cu. These data indicate that Kr irradiation induced mixing between Cu and FeCo, even though Cu is immiscible with Fe and Co in the equilibrium state.

Epitaxially stabilized TiN/(Ti,Fe,Co)N multilayer thin films in (pseudo-)fcc crystal structure by sequential magnetron sputter deposition

“…It is known that Fe x Co 1−x can be stabilized in the (pseudo-)fcc crystal structure at room temperature under appropriate conditions (choice of substrate, growth conditions and film thickness). These observations were frequently made at distinct dimensionalities such as pseudomorphically grown single-layer films [12,13], multilayer thin films [14] as well as nanocrystalline films [15]. However, the lattice constants of equiatomic (pseudo-)fcc FeCo (a FeCo = 0.354 nm [11]) and TiN (a TiN = 0.424 nm [16]) would yield a relative lattice mismatch of (a TiN − a FeCo )/a TiN = 0.165.…”

“…These observations were frequently made at distinct dimensionalities as pseudomorphically grown single layer films [12,13], multilayer thin films [14] as well as nanocrystalline films [15]. However, the lattice constants of equiatomic (pseudo-)fcc FeCo (a FeCo = 0.354 nm [11]) and TiN (a TiN = 0.424 nm [16]) would yield a relative lattice mismatch of ((a TiN −a FeCo )/a TiN = 0.165).…”