The amorphous iron-germanium system (a-FexGe1−x) lacks long-range structural order and hence lacks a meaningful Brillouin zone. The magnetization of a-FexGe1−x is well explained by the Stoner model for Fe concentrations x above the onset of magnetic order around x = 0.4, indicating that the local order of the amorphous structure preserves the spin-split density of states of the Fe-3d states sufficiently to polarize the electronic structure despite k being a bad quantum number. Measurements reveal an enhanced anomalous Hall resistivity ρ AH xy relative to crystalline FeGe; this ρ AH xy is compared to density functional theory calculations of the anomalous Hall conductivity to resolve its underlying mechanisms. The intrinsic mechanism, typically understood as the Berry curvature integrated over occupied k-states but shown here to be equivalent to the density of curvature integrated over occupied energies in aperiodic materials, dominates the anomalous Hall conductivity of a-FexGe1−x (0.38 ≤ x ≤ 0.61). The density of curvature is the sum of spin-orbit correlations of local orbital states and can hence be calculated with no reference to k-space. This result and the accompanying Stoner-like model for the intrinsic anomalous Hall conductivity establish a unified understanding of the underlying physics of the anomalous Hall effect in both crystalline and disordered systems.

Strong coupling stimulated Brillouin backscattering (sc-SBS) in plasma is potentially an efficient method of amplifying laser pulses to reach exawatt powers. Here, we report on a new regime of brillouin-based plasma amplification, producing an amplified pulse with a duration of 5 fs and unfocused intensity of 6 × 1017 W/cm2. The results are obtained from 2D particle-in-cell simulations, using two circularly polarized pump and seed pulse with Gaussian transverse profile, both at an intensity of 2.74 × 1016 W/cm2, counter-propagating in a 0.3nc plasma. The significant compression of amplified seed is achieved as a result of sc-SBS amplification as well as additional compression by the interplay between self-phase modulation and negative group delay dispersion. We show that the amplified seed retains high beam qualities since the filamentation can be prevented due to the fast compression. This scheme may pave the way for few-cycle laser pulses to reach exawatt or even zetawatt regime.

In 2 O 3 is a promising partner of InN to form InN/In2O3 heterosystems. The valence band offset (VBO) of wurtzite InN/cubic In2O3 heterojunction is determined by x-ray photoemission spectroscopy. The valence band of In2O3 is found to be 1.47±0.11 eV below that of InN, and a type-I heterojunction with a conduction band offset (CBO) of 0.49–0.99 eV is found. The accurate determination of the VBO and CBO is important for use of InN/In2O3 based electronic devices.

The shape of the self-assembled GeSi/Si(001) islands changed from a dome to a pyramid bounded with {103} or {105} facets after initial Si capping at 640 °C. The strains in the islands with initial Si capping are investigated by Raman spectroscopy. Compared with those of the uncapped islands, both peaks of Ge-Ge and Ge-Si vibration modes in the capped islands show blueshifts, corresponding to the Ge content decrease and the compressive strain increase in the capped islands. The total strain energy in an island is found to increase remarkably after Si capping. After simple analysis, it is found that the surface energy change could not overwhelm this large strain energy increase, making the shape transition favorable. It implies that the strain energy in the substrate in association with an island formation as well as evolution should be considered in accounting for the resulting island shape changes after Si capping.