Electronic structure, magnetic and optical properties of intermetallic compounds R2Fe17 (R=Pr,Gd)

In this paper we report comprehensive experimental and theoretical investigation of magnetic and electronic properties of the intermetallic compounds Pr2Fe17 and Gd2Fe17. For the first time electronic structure of these two systems was probed by optical measurements in the spectral range of 0.22-15 micrometers. On top of that charge carriers parameters (plasma frequency and relaxation frequency) and optical conductivity s(w) were determined. Self-consistent spin-resolved bandstructure calculations within the conventional LSDA+U method were performed. Theoretical interpetation of the experimental s(w) dispersions indicates transitions between 3d and 4p states of Fe ions to be the biggest ones. Qualitatively the line shape of the theoretical optical conductivity coincides well with our experimental data. Calculated by LSDA+U method magnetic moments per formula unit are found to be in good agreement with observed experimental values of saturation magnetization.Comment: 16 pages, 5 figures, 1 tabl

Optical spectroscopy and electronic structure of compounds HoNi 5-x Alx (x = 0, 1, 2)

The optical properties of the compounds HoNi5 - x Al x (x = 0, 1, 2) have been investigated using the ellipsometric method in the wavelength range from 0.22 to 16 μm. The electronic structure of these intermetallic compounds has been calculated in the local electron-spin density approximation with the correction for strong electronic interactions in the 4f shell of the holmium ions. The experimental dispersion dependences of optical conductivity in the region of interband light absorption have been interpreted based on the results of the calculation of the electron density of states. The plasma and relaxation frequencies of electrons have been determined. © 2013 Pleiades Publishing, Ltd

Detection of mechanical resonance of a single-electron transistor by direct current

We have suspended an Al based single-electron transistor whose island can resonate freely between the source and drain leads forming the clamps. In addition to the regular side gate, a bottom gate with a larger capacitance to the SET island is placed underneath to increase the SET coupling to mechanical motion. The device can be considered as a doubly clamped Al beam that can transduce mechanical vibrations into variations of the SET current. Our simulations based on the orthodox model, with the SET parameters estimated from the experiment, reproduce the observed transport characteristics in detail.Comment: 4 pages, 3 figure

Experimental and theoretical investigations on magnetic and related properties of ErRuSi

We report experimental and theoretical studies of magnetic and related properties of ErRuSi compound. Various experimental techniques such as neutron diffraction, magnetization, magneto-thermal, magneto-transport, optical have been used to study the compound. Neutron diffraction shows ferromagnetic ordering at low temperatures with moments aligned in ab plane. Neutron diffraction and magnetization data show reduction in magnetic moment, which may be due to crystalline electric field effects at low temperatures. The compound shows good magnetocaloric properties with a low field adiabatic temperature change of 4.7 K, which is larger than that of many proposed materials for magnetic refrigeration at low temperatures. Magnetoresistance shows large negative value at 8 K, which changes its sign and increases in magnitude, with decrease in temperature and/or increase in field. The positive MR at low temperatures attributed to the Lorentz force effect. The electronic structure calculations accounting for electronic correlations of the 4f electrons of Er reproduces the ferromagnetic ordering and effective magnetic moment. Interband transitions between the Ru and Er d states and Er f states in one spin projection are found to form the main features of the measured optical conductivity in this compound.Comment: 14 pages, 10 figure

Electronic Structure, Magnetic, and Optical Properties of the Intermetallic Compounds R2 Fe17 (R=Pr,Gd)

In this paper we report comprehensive experimental and theoretical investigation of magnetic and electronic properties of the intermetallic compounds Pr2 Fe17 and Gd2 Fe17. Electronic structure of these two systems was probed by optical measurements in the spectral range of 0.22-15 μm. On top of that, charge-carrier parameters (plasma frequency Ω and relaxation frequency γ) and optical conductivity σ(ω) were determined. Self-consistent spin-resolved band-structure calculations within the conventional LSDA+U method were performed. Theoretical interpretation of the experimental σ(ω) dispersions indicates transitions between 3d and 4p states of Fe ions to be the biggest ones. Qualitatively the line shape of the theoretical optical conductivity coincides well with our experimental data. Calculated by the LSDA+U method magnetic moments per formula unit are found to be in good agreement with observed experimental values of saturation magnetization. © 2006 The American Physical Society.This work was supported by Grants from the Russian Foundation for Basic Research, Grant Nos. 05-02-17244, 04-02-16096, and 05-02-16301 and in part by programs of the Presidium of the Russian Academy of Sciences (RAS) “Quantum macrophysics” and of the Division of Physical Sciences of the RAS “Strongly correlated electrons in semiconductors, metals, superconductors and magnetic materials.” Two of us I.N., A.L. acknowledge Dynasty Foundation and International Center for Fundamental Physics in Moscow and Russian Science Support Foundation, Grant of President of Russia MK-02.2118.2005 and interdisciplinary UrO-SO project (I.N.)