Epitaxy and alloying at the CoPt(111) interface: a study by X-ray photoelectron diffraction

Formation of L10-ordered CoPt during interdiffusion of electron-beam-deposited Pt/Co bilayer thin films on Si/SiO2 substrates by rapid thermal annealing

“…At 300°C, alloying of the Co and Pt atoms in the film was clearly observed as the diffraction peaks originating from A1-disordered CoPt 111, 200, 220, and 311 (blue arrows, figure 3(c)). This alloying temperature agrees well with previous studies using x-ray photoelectron diffraction [44] and Auger electron spectroscopy [45]. Moreover, based on the related reports [44,45], a Co-rich region, equiatomic region, and Pt-rich region could potentially exist in the vicinity of the initial interface of the Pt/Co bilayer films after annealing at 300°C, which would result in the formation of all-proportional solid solutions of CoPt alloys.…”

Surface alloys and alloy surfaces: the platinum-tin system

“…The observation of a well defined periodicity in LEED for the Sn/Pt(111) system and the parallel indications of the presence of tin in the subsurface in amount corresponding to approximately 25 at% indicates that we have a true ordered compound which extends for several atomic layers [37]. This behavior appears to be similar to that of the Co-Pt system [94], although in the case of Sn-Pt it was not possible to evidence the same kind of sharp alloy/substrate interface reported for Co/Pt(111). The possibility of obtaining a compound with negative enthalpy of formation is surely a factor favoring the formation of a multilayer homogeneous alloy in this sytem however, in this as in other systems, kinetic factors may be more important, and in particular factors related to the presence of grain boundaries in the deposited film.…”

“…Other case known where this occurs are the Au-Cu(100) [92] and the Pd-Cu(001) [93] systems. In other cases, such as Co-Pt(111) [94], only multilayer surface alloys are known to form, although alloying appears to be limited to the outermost 2 surface layers only. So far, the structure of most of these surface phases turned out to be the one that maximizes the number of heterogeneous pairwise interactions.…”

Irreversible modification of magnetic properties of Pt/Co/Pt ultrathin films by femtosecond laser pulses

“…Treating the sample thermally may lead, depending on the used materials, to improvement or degradation of that quality. For Pt/Co/Pt interfaces, due to a large negative enthalpy of alloy formation at elevated temperature, 5 annealing leads to intermixing of atoms in neighboring layers, 6 followed by a decrease of the magnetic anisotropy. 7,8 On the contrary, initially poor interfaces of Au/Co/Au structures can be improved by annealing (due to immiscibility of Co and Au), resulting in a creation of the out-of-plane magnetic phase.…”