We study the evolution of the electronic structure of the intermetallic series Gd 6 (Mn 1−x Fe x ) 23 , x = 0.0-0.75, which shows nonmonotonic ferrimagnetic ordering temperatures T C but with a systematic reduction of the total bulk magnetization upon increasing Fe content, x. We have carried out hard x-ray photoemission spectroscopy to elucidate the relation between electronic structure and properties of the series. The Gd 3d and Gd 4d corelevel spectra indicate trivalent Gd 3+ multiplets in the intermediate-coupling scheme with features due to L-S and j-J coupling. The Fe 2p core levels show asymmetric single peak metal-like spectra, while the Mn 2p core levels show asymmetric doublet peaks. The relative intensities of the Mn 2p doublets as a function of x indicate occupancy changes of distinct crystallographic sites associated with Mn up-spin and down-spin states. The valence band spectra identify the Gd 4 f states at high binding energies (∼7.4 eV). The Mn 3d states occur at the Fermi level and as a broad feature between 2 and 5 eV binding energy in Gd 6 Mn 23 . Upon substitution, the Fe 3d states show up as small shifts to higher binding energies compared to Mn 3d states. The Fe 3s and Mn 3s spectra show exchange split peaks, allowing an estimate of the Mn and Fe magnetic moments using a Van Vleck analysis, which also provides a quantification of occupancy changes with x. The overall results are consistent with the bulk net magnetization, indicating that Mn up-spin sites become Fe down-spin sites on substitution, while the nonmonotonic T C originates in a change from Mn sublattice to Fe sublattice derived ordering.

Conventional vapor–liquid–solid mechanism of nanowire growth opens up new opportunities of fabricating nanowires with controllable morphologies and aspect ratios. However, gaseous precursors have disadvantages of high material and processing cost, high toxicity, and limited scalability. By contrast, synthesizing nanowires via solid–liquid–solid mechanism could be a facile alternative since the low cost and nontoxic solid precursor is adopted in the process. In this study, the cooling control is found to be very critical for the solid–liquid–solid nanowire growth. Without a sufficient negative vertical temperature gradient, the nucleation and continuous growth of silicon nanowires could not occur. High volume gas flow cooling, fluctuating the heating temperature, decreasing the cooling rate, and applying a heat sink are all efficacious to promote silicon nanowire formation. In addition to the nanowires formed under high gas flow cooling on the silicon wafer sputtered with a nickel thin film, the solid–liquid–solid mechanism‐derived silicon nanowire growth can also be economically achieved by adopting a solution‐based coating of a nickel precursor onto the silicon substrate paired with a programmed slow cooling condition without using any gas, which could be transferred to other eutectic systems for cost‐effective nanomaterial fabrication.

We study the electronic structure of single-crystal Tb 0.5 Sr 0.5 MnO 3 , a non-charge-ordered mixed-valent semiconductor which exhibits a glassy magnetic ground state. We use the techniques of soft x-ray photoemission, hard x-ray photoemission, x-ray absorption, and resonant photoemission spectroscopy to investigate the occupied and unoccupied electronic states of Tb 0.5 Sr 0.5 MnO 3 . Core level photoemission and x-ray absorption spectroscopy allow us to determine the valence states of Tb, Sr, and Mn ions in Tb 0.5 Sr 0.5 MnO 3 . Model charge transfer multiplet calculations of core level photoemission and x-ray absorption spectra are employed to separate out the Mn 3+ and Mn 4+ states and confirm their relative concentrations. Resonant photoemission spectroscopy across the Mn 2p-3d threshold shows clear resonant enhancement of the Mn 3d partial density of states and two-hole correlation satellites. A Cini-Sawatzky analysis gives on-site Coulomb energy U dd ∼ 5.5 ± 0.2 eV for the Mn 3d n states and U pd = 0.7 eV ± 0.2 eV for the Mn 3d n+1 L 1 states. The O 1s-2p resonant photoemission is used to identify the O 2p two-hole correlation satellite which provides U pp ∼ 3.4 ± 0.2 eV for the O 2p states. Valence band photoemission indicates a small-gap semiconductor (<100 meV) consistent with electrical transport measurements. The estimated electronic structure parameters of the on-site Coulomb energies, in combination with the charge transfer energy and the hybridization strength obtained from the model calculations, indicate that Tb 0.5 Sr 0.5 MnO 3 is a strongly correlated charge transfer type semiconductor.