Electronic structure of RE1-xAxMnO3 manganite films investigated by magnetic circular dichroism spectroscopy

Magnetic circular dichroism (MCD) spectroscopy was used to study the features of the electronic structure of an epitaxial La0.7Ca0.3MnO3 film in the range of 1.2 - 4 eV. The study of the temperature behavior of the MCD spectra made it possible to establish a correlation between the magnetooptical and transport properties of the sample. The data obtained were analyzed in comparison with MCD data for polycrystalline manganite films of various RE1-xAxMnO3 compositions. The MCD spectra of the films were compared with the spectra of the off-diagonal component of the permittivity tensor calculated from the data of the magneto-optical Kerr effect for films of the same composition. A unified set of ground and excited electronic states characteristic of RE1-xAxMnO3 manganites in the visible and near infrared ranges has been identified. These results are important for a qualitative theoretical description of the electronic structure of strongly correlated magnetic oxides.Comment: 5 figures, 2 table

Semiconducting Electronic Structure of the Ferromagnetic Spinel HgCr2Se4\mathbf{Hg}\mathbf{Cr}_2\mathbf{Se}_4 Revealed by Soft-X-Ray Angle-Resolved Photoemission Spectroscopy

We study the electronic structure of the ferromagnetic spinel $\mathrm{Hg}\mathrm{Cr}_2\mathrm{Se}_4$ by soft-x-ray angle-resolved photoemission spectroscopy (SX-ARPES) and first-principles calculations. While a theoretical study has predicted that this material is a magnetic Weyl semimetal, SX-ARPES measurements give direct evidence for a semiconducting state in the ferromagnetic phase. Band calculations based on the density functional theory with hybrid functionals reproduce the experimentally determined band gap value, and the calculated band dispersion matches well with ARPES experiments. We conclude that the theoretical prediction of a Weyl semimetal state in $\mathrm{Hg}\mathrm{Cr}_2\mathrm{Se}_4$ underestimates the band gap, and this material is a ferromagnetic semiconductor.Comment: 6+13 pages, 4+13 figure

Magnetic Semiconductors as Materials for Spintronics

From the various aspects of spintronics the review highlights the area devoted to the creation of new functional materials based on magnetic semiconductors and demonstrates both the main physical phenomena involved and the technical possibilities of creating various devices: maser, p-n diode with colossal magnetoresistance, spin valve, magnetic lens, optical modulators, spin wave amplifier, etc. Particular attention is paid to promising research directions such as ultrafast spin transport and THz spectroscopy of magnetic semiconductors. Special care has been taken to include a brief theoretical background and experimental results for the new spintronics approach employing magnetostrictive semiconductors-strain-magnetooptics. Finally, it presents top-down approaches for magnetic semiconductors. The mechano-physical methods of obtaining and features of the physical properties of high-density nanoceramics based on complex magnetic oxides are considered. The potential possibility of using these nanoceramics as an absorber of solar energy, as well as in modulators of electromagnetic radiation, is shown

Magnetic Semiconductors as Materials for Spintronics

From the various aspects of spintronics the review highlights the area devoted to the creation of new functional materials based on magnetic semiconductors and demonstrates both the main physical phenomena involved and the technical possibilities of creating various devices: maser, p-n diode with colossal magnetoresistance, spin valve, magnetic lens, optical modulators, spin wave amplifier, etc. Particular attention is paid to promising research directions such as ultrafast spin transport and THz spectroscopy of magnetic semiconductors. Special care has been taken to include a brief theoretical background and experimental results for the new spintronics approach employing magnetostrictive semiconductors—strain-magnetooptics. Finally, it presents top-down approaches for magnetic semiconductors. The mechano-physical methods of obtaining and features of the physical properties of high-density nanoceramics based on complex magnetic oxides are considered. The potential possibility of using these nanoceramics as an absorber of solar energy, as well as in modulators of electromagnetic radiation, is shown

Strain-Magnetooptics in Single Crystals of CoFe₂O₄

The strain-magnetooptical properties of single crystals of the ferrimagnetic spinel CoFe2O4, which reflect a correlation between optical properties (magnetoabsorption and magnetoreflection) and magnetostriction, have been studied in the infrared spectral range. The conditions for the observation of the strain-magnetooptics are specified and physical mechanisms responsible for these effects in the spinel are explained