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Abstract: Bulk Sm1− x Gd x Al2 (0.003

A detailed structural analysis of the epitaxial growth of europium using in situ reflection high-energy electron diffraction has been performed for two kinds of buffer layers with different symmetry: (1 1 0)niobium (Nb) and (0 0 0 1)yttrium (Y). Moreover, by varying the preparation conditions of the (1 1 0)Nb layer we get either a reconstructed or an unreconstructed Nb surface, which turns out to have a strong influence on the Eu growth: the reconstructed (1 1 0)Nb surface favours the stabilisation of an Eu hexagonal surface structure, as well as the (0 0 0 1)Y buffer, whereas a pure unreconstructed (1 1 0)Nb surface enables the growth of single crystalline bcc (1 1 0)Eu films. With increasing Eu thickness, the relaxation of the metastable Eu hexagonal surface obtained on (0 0 0 1)Y or on reconstructed (1 1 0)Nb gives rise to a multidomain structure that drastically depends on the nature of the underlying buffer layer. [Copyright &y& Elsevier]

Abstract: The epitaxial growth of (110) and (111) SmAl2 thin films has been achieved on (110)Nb∥(112¯0) sapphire by molecular beam epitaxy. The successful fabrication of this compound as thin films is the first and promising step towards the growth of thin films of the ternary compound Sm1− x Gd x Al2, a zero magnetization ferromagnet of high interest for magnetic nanodevices. We report especially on the influence of the deposition temperature on the growth direction of SmAl2: in-situ RHEED analysis and ex situ large angle X-ray scattering experiments show that the growth direction evolves from [111] to [110] when the deposition temperature increases from 510 to 620°C. The (110) films stabilized at higher temperature present twins rotated by 70° about the surface normal, whereas the (111) films are twin-free single domains. Results are correlated to the film morphology at the beginning of growth, observed by AFM, which depends also significantly on the deposition temperature. The strains measured parallel to the growth direction depend slightly on the film thickness and are larger than those expected from the substrate thermal contraction after deposition. [Copyright &y& Elsevier]

Abstract: Single crystal Eu(110) films exhibit an atypical magnetic arrangement, different from the bulk three helices configuration: at low temperature, under zero field, only two magnetic domains are present since the magnetic helix that propagates along the in-plane [001] axis disappears below a given temperature. This paper presents the study of the stability of the magnetic domains under magnetic field using neutron scattering experiments and magnetisation measurements on a 375nm thick Eu(110) film. The helix propagating along [001] is restored by the application of an external field along the [001] direction, which gives rise to a supplemental Zeeman contribution. [Copyright &y& Elsevier]

Magnetic phases and coherence have been investigated in a (0 0 1) Sm/Nd superlattice using Resonant X-ray magnetic scattering. The magnetic phases in Sm layers are similar to the ones evidenced in double hexagonal compact thick films. On the contrary, the magnetism in Nd layers exhibits strong differences with the bulk case, especially the occurrence of a new low-temperature phase. Moreover, the magnetic order on the hexagonal Nd sites propagates coherently through magnetic Sm layers, whereas the coherence length of the Nd cubic order is limited to individual Nd layers. [Copyright &y& Elsevier]