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Electronic structure of BiFe 1-x Mn x O 3 thin films investigated by X-ray absorption spectroscopy

Multiferroic polycrystalline BiFe1-xMnxO3 (0 ≤ x ≤ 0.3) thin films have been prepared on the Pt(111)/Ti/SiO2/Si(100) substrates by pulsed laser deposition method. The influence of Mn substitution on the electronic structure and magnetic properties has been studied. X-ray diffraction spectroscopy shows that Mn substitution slightly modulates crystal structure of the BiFe1-xMnxO3 system within the same structural phase. According to Fe L edge X ray absorption spectroscopy, Fe ions are found to be formally trivalent for doping amount x in BiFe1-xMnxO3. The enhanced magnetization by increasing Mn content is attributed to an alternation degree of hybridization between Fe 3d-O 2p and Mn 3d-O 2p orbitals, basing on the carefully examined Fe L and O K edge X-ray absorption spectroscopy. The crystal structural and the electronic structural results show a causal relation between them by demonstrating intrinsic mutual dependence between respective variations.

Al Vacancy Induced Room-Temperature Ferromagnetic in Un-Doped AlN

Room-temperature ferromagnetism has been found in AlN grown by direct arc discharge method using the direct reaction of Al powder with N2 gas. The observed room-temperature ferromagnetism which arises from the aluminum vacancy is intrinsic properties in AlN. The results could rule out oxygen impurities as the main cause of magnetic origin in AlN. First-principles calculations reveal that spontaneous spin polarization creates with a 3.0 uBlocal moment for AlN and magnetic originate from the polarization of the unpaired 2p electrons of N surrounding the Al vacancy. The aluminum vacancy induced may be applicable to other Ш-V nitride semiconductors in turning their magnetism.

In situ electronic structure investigation ofMn doped BiFeO3 thin films

The electronic structure of BiFe1-xMnxO3 (0≤x≤0.3) thin films has been investigated by in situ near edge X-ray absorption fine structure (NEXAFS) and photoemission spectroscopy.Fe ions are found to be trivalent for the whole range of x in BiFe1-xMnxO3 and a hybridization between the Fe 3d and O 2p states is decreased by increasing Mn concentration. Charge transfer multiplet (CTM) calculation is used to understand the experimental results of the Fe L-edge spectra. The experimental results plus the CTM calculation showsthe hybridization degree between the transition metal 3d and O 2p states areplay important role for the multiferroic properties of underlying systems.