Abstract
The report is devoted to an analysis of the structural and magnetic state of the nanocrystalline diluted magnetic semiconductors based on TiO2 doped with Fe and Co atoms. Structural and magnetic characterization of samples was carried out using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR) spectroscopy, SQUID magnetometry, and the density functional theory (DFT) calculations. Analysis of the experimental data suggests the presence of non-interacting paramagnetic Fe3+ and Co2+ ions in the high-spin state and negative exchange interactions between them. The important conclusions is that the distribution of dopants in the TiO2 matrix, even at low concentrations of 3d-metal dopant (less than one percent), is not random, but the 3d ions localization and dimerization is observed both on the surface and in the nanoparticles core. Thus, in the paper the quantum mechanical model for describing the magnetic properties of TiO2:(Fe, Co) was suggested. The model operates only with two parameters: paramagnetic contribution of non-interacting 3d-ions and dimers having different exchange interactions between 3d magnetic carriers.
Highlights
Structural and magnetic characterization of samples was carried out using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR) spectroscopy, SQUID magnetometry, and the density functional theory (DFT) calculations
This report is based on the results of investigation of the structure, the ground magnetic and electronic states of the refined nanocrystalline systems TiO2:(Co, Fe) with the anatase crystal structure taking into account the paramagnetic contribution, dimerization and dimensionality of the systems [1,2,3]
The quantum-mechanical model takes into account the non-interacting 3d-ions and dimers with different negative exchange interactions, allow describing quite effectively the magnetic properties of the mentioned system
Summary
A Yermakov, D Boukhvalov, M Uimin, V Mesilov, A Minin, V Galakhov, A Korolyov, A Volegov, E Rosenfeld, A Gubkin and L Molochnikov.
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