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X-ray scattering and electrical resistivity measurements were performed on SmNiC2. Satellite peaks characterized by an incommensurate wave vector (0.5, eta, 0) appear below 148 K, at which the resistivity shows an anomaly. The temperature dependence of thermal diffuse scattering above 148 K suggests critical phonon softening. These results indicate the formation of a charge-density-wave. The satellite peaks abruptly disappear and the resistivity sharply decreases when a ferromagnetic transition takes place at 17.7 K.

GaAs/GaAsBi coaxial multishell nanowires were grown by molecular beam epitaxy. Introducing Bi results in a characteristic nanowire surface morphology with strong roughening. Elemental mappings clearly show the formation of the GaAsBi shell with inhomogeneous Bi distributions within the layer surrounded by the outermost GaAs, having a strong structural disorder at the wire surface. The nanowire exhibits a predominantly ZB structure from the bottom to the middle part. The polytipic WZ structure creates denser twin defects in the upper part than in the bottom and middle parts of the nanowire. We observe room temperature cathodoluminescence from the GaAsBi nanowires with a broad spectral line shape between 1.1 and 1.5 eV, accompanied by multiple peaks. A distinct energy peak at 1.24 eV agrees well with the energy of the reduced GaAsBi alloy band gap by the introduction of 2% Bi. The existence of localized states energetically and spatially dispersed throughout the NW are indicated from the low temperature cathodoluminescence spectra and images, resulting in the observed luminescence spectra characterized by large line widths at low temperatures as well as by the appearance of multiple peaks at high temperatures and for high excitation powers.

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We control the formation of Bi-induced nanostructures on the growth of GaAs/GaAsBi core–shell nanowires (NWs). Bi serves as not only a constituent but also a surfactant and nanowire growth catalyst. Thus, we paved a way to achieve unexplored III–V nanostructures employing the characteristic supersaturation of catalyst droplets, structural modifications induced by strain, and incorporation into the host GaAs matrix correlated with crystalline defects and orientations. When Ga is deficient during growth, Bi accumulates on the vertex of core GaAs NWs and serves as a nanowire growth catalyst for the branched structures to azimuthal <112>. We find a strong correlation between Bi accumulation and stacking faults. Furthermore, Bi is preferentially incorporated on the GaAs (112)B surface, leading to spatially selective Bi incorporation into a confined area that has a Bi concentration of over 7%. The obtained GaAs/GaAsBi/GaAs heterostructure with an interface defined by the crystalline twin defects in a zinc-blende structure can be potentially applied to a quantum confined structure. Our finding provides a rational design concept for the creation of GaAsBi based nanostructures and the control of Bi incorporation beyond the fundamental limit.

Results of non-resonant X-ray Bragg diffraction by CeB6 are reported. This material has been described in terms of a simple antiferro-quadrupolar order below TQ = 3.2 K. We determine for the first time, directly and quantitatively the orbital ordering in this material. In particular, we find direct evidence for a simultaneous ordering of a quadrupole (QP) and a hexadecapole (HDP) moments below TQ. From a strong dependence of the Bragg intensity on applied magnetic field in phase II, we conclude that octupole (OP) moments are induced and are coupled to the QP and HDP moments. When spontaneous magnetic dipole order sets in below TN = 2.4 K (phase III), a large enhancement of the Bragg intensity confirms the coupling between the dipole and the QP, OP and HDP moments.