ZnO wires are prepared from the oxidation of Zn wires, which are electrodeposited into AAO template. The ZnO wires show ferromagnetism at room temperature. A detailed study indicates that, owing to incomplete oxidation, Zn clusters embedded in the ZnO matrix may attribute to the room‐temperature ferromagnetism.

By coupling two nonlinear one dimensional lattices, we demonstrate a thermal diode model that works in a wide range of system parameters. We provide numerical and analytical evidence for the underlying mechanism which allows heat flux in one direction while the system acts like an insulator when the temperature gradient is reversed. The possible experimental realization in nano scale systems is briefly discussed.

Absence of ferromagnetism in single-phase wurtzite Zn 1 − x Mn x O polycrystalline thin filmsWe present a comprehensive study relating the magnetic properties to structural properties of Mn + -implanted Si 1−x Ge x films as a function of Ge content ͑x =0-0.5͒. Ferromagnetic ordering with three critical temperatures, T B ϳ 10-16 K, T C1 ϳ 650-780 K, and T C2 ϳ 825-860 K, are reported in this material system. Element specific x-ray absorption fine structure results show that the majority of the Mn ions are nonsubstitutional in all samples. The transmission-electron microscopy coupled with z contrast and chemical analysis reveals the presence of Mn-rich nanosized clusters including Mn 4 Si 7 in Si-rich samples and Mn 7 Ge 3 phases in Ge-rich samples. A composition transition occurred at x ϳ 0.2-0.3, where we observe a change in bond lengths and defect structures. Additionally, an enhancement in magnetizations with an increase in both T B and T C1 as well as a conversion from n-type to p-type conduction are also detected.

The electronic structure of cobalt-induced magic clusters grown on Si͑111͒-͑7 ϫ 7͒ is investigated by scanning tunneling microscopy, scanning tunneling spectroscopy, and real-space multiple-scattering calculations. Topographical images of a half unit cell of Si͑111͒-͑7 ϫ 7͒ with the cluster acquired at low bias voltages of ±0.4 V show greatly reduced cluster heights; however, the heights of the corner adatoms are unchanged, indicative of the highly localized nature of the charge distribution. Spectroscopic studies of the clusters indicate a band gap of ϳ0.8 eV, suggesting localized nonmetallic behavior. The opening of such a band gap is suggested to be a stabilizing factor for the observed magic clusters. A 65-atom Co-Si cluster is constructed to calculate the momentum-and element-projected density of states. The calculated result identifies that the intense state below the Fermi level at −1.75 V in the experimental spectroscopic curve is primarily due to localized 3d orbitals of Co atoms in the magic clusters.

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