Semiconductors doped with magnetic ions, also known as dilute magnetic semiconductors, are both semiconducting and ferromagnetic. It remains unclear, however, whether this ferromagnetism is intrinsic, as is required for spintronic applications, or is due instead to dopant clustering. Here, we report conclusive evidence for intrinsic ferromagnetism in individual ZnO nanoparticles doped with transition metal ions. Through a simultaneous magnetic and microstructural characterization using electron magnetic chiral dichroism and channelling-enhanced electron energy loss microanalysis, respectively, we show that ZnO nanoparticles have intrinsic ferromagnetism when doped with cobalt, but not when doped with iron.

The layered structures of La 0.67 Sr 0.33 MnO 3 /SrTiO 3 superlattices have been investigated by energy filtered transmission electron microscopy (EFTEM) and spatially resolved electron energy loss spectroscopy (EELS). A general picture of the elemental distribution of the chemically modulated layers was given by the EFTEM images. Chemical shift in both Ti-L 2,3 and Mn-L 2,3 edges, together with an appearance of distinctive shoulders in both Mn-L 3 and Mn-L 2 edges at the interfacial region were observed. These electronic structure changes suggest a stronger crystal field and/or a partial loss of oxygen at the interfaces, accounting for the observed oscillatory exchange coupling and enhanced magnetoresistance in such superlattices.

Luminescent properties and electronic structures of rare earth and alkaline earth borates of RE Ba 3 B 9 O 18 ( RE = Lu , Y )Using valence electron energy loss spectroscopy and ab initio band structure calculations, we have studied the basic electronic structure of a potential optical crystal YBa 3 B 9 O 18 . Its optical band gap E g is experimentally estimated as 6.3 eV and the origins of the individual interband transitions have been identified. In addition, the theoretical calculation reveals the strong anisotropic characteristic of the material band structure, accounting for its large birefringence.

The luminescence mechanisms of a potential scintillation crystal YBa 3 B 9 O 18 were investigated by experimental methods. As a first step, the optical band gap energy Eg was estimated to be 7.3 eV from the optical absorption spectrum and vacuum ultraviolet excited luminescence spectra. The X-ray photoelectron spectroscopy measured in the valence region coincided with the first principle energy band calculation. Based on the analysis of valence band structure and vacuum ultraviolet excited luminescence spectra the origins of emission bands of YBa 3 B 9 O 18 were studied. The intrinsic luminescence of YBa 3 B 9 O 18 was attributed to the radiative decay of self-trapped excitons. The elucidation of the luminescence mechanism provides a physical picture on the property-structure correlation and may help to accelerate the applications of the potential scintillation crystal.

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