Epitaxial growth of strained Mn₅Ge₃nanoislands on Ge(001)

Abstract

We report on the epitaxial growth of Mn5Ge3 on Ge(001) by molecular beam epitaxy using solid phase epitaxy method. Mn5Ge3 grows as nanoislands, which are randomly distributed over the substrate surface. Select area electron diffraction analysis was used to determine the epitaxial relationship Mn5Ge3(001)[110]//Ge(001)[110], as well as to detect an induced tensile strain along [110] Mn5Ge3 direction to fit the Ge lattice, while the observation of Moiré patterns indicates a complete relaxation along the [11¯0] direction. In‐plane and out‐of‐plane M(H) loops were obtained at 200 K using a vibrating sample magnetometer, it was found that the easy axis of magnetization is perpendicular to the substrate surface and that the crystal magnetic anisotropy is K1 = 9.27 × 105 erg cm−3. The enhancement of the Curie temperature of the nanoislands ∼340 K, which is higher than 296 K of the bulk Mn5Ge3, is attributed to the induced strains.

From the Very First Stages of Mn Deposition on Ge(001) to Phase Segregation

“…A subsequent anneal of the nanoislands leads to the formation of Mn 5 Ge 3 as demonstrated by Olive et al The growth of the Mn 5 Ge 3 phase on Ge(001) is remarkable because it is endotaxial: its interface is buried in the substrate, as shown in Figure d. Indeed, only part of the island emerges from the surface, the rest being buried in the substrate of Ge(001).…”

“…35 The similarities in spatial distribution, shape and density between the nanoislands (Fig. 5a) and the nanocolumns system A subsequent anneal of the nanoislands leads to the formation of Mn 5 Ge 3 as demonstrated by Olive et al 37 The growth of the Mn 5 Ge 3 phase on Ge(001) is remarkable because endotaxial: its interface is buried in the substrate, as shown in Fig. 5d.…”

“…The experimental conditions (T G , Mn concentration, slow deposition rates) determine the nanocolumns characteristics (size, density, composition) that result from a competition between chemical, elastic, and interfacial energy terms. 36 A subsequent anneal of the nanoislands leads to the formation of Mn 5 Ge 3 as demonstrated by Olive et al 37 The growth of the Mn 5 Ge 3 phase on Ge(001) is remarkable because it is endotaxial: its interface is buried in the substrate, as shown in Figure 5d. Indeed, only part of the island emerges from the surface, the rest being buried in the substrate of Ge(001).…”

Strong magnetization and anisotropy of Mn5Ge3 thin films on Ge(001)

“…It has been demonstrated that Mn 5 Ge 3 /Ge(111) thin films, where the c axis of Mn 5 Ge 3 is perpendicular to the film plane, have their easy magnetization axis on the basal Mn 5 Ge 3 (001) plane, for films with thickness <25 nm [21]. This is an opposite behavior to the one of bulk or nanostructured Mn 5 Ge 3 , where the c axis is also the easy magnetization axis [17,21]. It has been observed that the magnetic anisotropy is directly related to the thickness of Mn 5 Ge 3 /Ge(111) films.…”

“…Mn 5 Ge 3 grown on Ge(111) is also proposed as a potential prospect for SC/FM heterostructures for spin injection [16]. However, the growth of Mn 5 Ge 3 on Ge(001) substrates has been scarcely investigated [9,[17][18][19]. Mn 5 Ge 3 /Ge(001)heterostructures offer the possibility of integration into the Si(001) production technology, as Ge epitaxial layers can be grown on Si(001) substrates, through a (001) SiGe interlayer [20].…”