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Articles 1 - 7 of 7
Full-Text Articles in Physics
Ferroelectric Switch For Spin Injection, Mikhail Y. Zhuravlev, Sitaram Jaswal, Evgeny Y. Tsymbal, Renat F. Sabirianov
Ferroelectric Switch For Spin Injection, Mikhail Y. Zhuravlev, Sitaram Jaswal, Evgeny Y. Tsymbal, Renat F. Sabirianov
Physics Faculty Publications
A method for the switching of the spin polarization of the electric current injected into a semiconductor is proposed, based on injecting spins from a diluted magnetic semiconductor through a ferroelectric tunnel barrier. We show that the reversal of the electric polarization of the ferroelectric results in a sizable change in the spin polarization of the injected current, thereby providing a two-state electrical control of this spintronic device. We also predict a possibility of switching of tunneling magnetoresistance in magnetic tunnel junctions with a ferroelectric barrier and coexistence of tunneling magnetoresistance and giant electroresistance effects in these multiferroic tunnel junctions.
Domain-Wall Magnetoresistance Of Co Nanowires, Renat F. Sabirianov, Ashok K. Solanki, J. D. Burton, Sitaram S. Jaswal, Evgeny Y. Tsymbal
Domain-Wall Magnetoresistance Of Co Nanowires, Renat F. Sabirianov, Ashok K. Solanki, J. D. Burton, Sitaram S. Jaswal, Evgeny Y. Tsymbal
Physics Faculty Publications
Using density functional theory implemented within a tight-binding linear muffin-tin orbital method we perform calculations of electronic, magnetic, and transport properties of ferromagnetic free-standing fcc Co wires with diameters up to 1.5 nm. We show that finite-size effects play an important role in these nanowires resulting in oscillatory behavior of electronic charge and the magnetization as a function of the wire thickness, and a nonmonotonic behavior of spin-dependent quantized conductance. We calculate the magnetoresistance (MR) of a domain wall (DW) modeled by a spin-spiral region of finite width sandwiched between two semi-infinite Co wire leads. We find that the DW …
Giant Electroresistance In Ferroelectric Tunnel Junctions, Mikhail Y. Zhuravlev, Renat F. Sabirianov, Sitaram Jaswal, Evgeny Y. Tsymbal
Giant Electroresistance In Ferroelectric Tunnel Junctions, Mikhail Y. Zhuravlev, Renat F. Sabirianov, Sitaram Jaswal, Evgeny Y. Tsymbal
Physics Faculty Publications
The interplay between the electron transport in metal-ferroelectric-metal junctions with ultrathin ferroelectric barriers and the polarization state of a barrier is investigated. Using a model which takes into account screening of polarization charges in metallic electrodes and direct quantum tunneling across a ferroelectric barrier, we calculate the change in the tunneling conductance associated with the polarization switching. We find the conductance change of a few orders of magnitude for metallic electrodes with significantly different screening lengths. This giant electroresistance effect is the consequence of a different potential profile seen by transport electrons for the two opposite polarization orientations.
Strain Induced Half-Metal To Semiconductor Transition In Gdn, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy
Strain Induced Half-Metal To Semiconductor Transition In Gdn, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy
Physics Faculty Publications
We investigate the electronic structure and magnetic properties of GdN as a function of unit cell volume. Based on the first-principles calculations of GdN, we observe that there is a transformation in the conduction properties associated with the volume increase: first from half-metallic to semimetallic, then ultimately to semiconducting. We show that applying stress can alter the carrier concentration as well as mobility of the holes and electrons in the majority spin channel. In addition, we found that the exchange parameters depend strongly on lattice constant, thus the Curie temperature of this system can be enhanced by applying stress or …
Ballistic Anisotropic Magnetoresistance, Julian P. Velev, Renat F. Sabirianov, Sitaram Jaswal, Evgeny Y. Tsymbal
Ballistic Anisotropic Magnetoresistance, Julian P. Velev, Renat F. Sabirianov, Sitaram Jaswal, Evgeny Y. Tsymbal
Physics Faculty Publications
Electronic transport in ferromagnetic ballistic conductors is predicted to exhibit ballistic anisotropic magnetoresistance—a change in the ballistic conductance with the direction of magnetization. This phenomenon originates from the effect of the spin-orbit interaction on the electronic band structure which leads to a change in the number of bands crossing the Fermi energy when the magnetization direction changes. We illustrate the significance of this phenomenon by performing ab initio calculations of the ballistic conductance in ferromagnetic Ni and Fe nanowires which display a sizable ballistic anisotropic magnetoresistance when magnetization changes direction from parallel to perpendicular to the wire axis.
Dielectric Properties And Maxwell-Wagner Relaxation Of Compounds Acu3ti4o12 (A=Ca,Bi2/3,Y2/3,La2/3), Jianjun Liu, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy
Dielectric Properties And Maxwell-Wagner Relaxation Of Compounds Acu3ti4o12 (A=Ca,Bi2/3,Y2/3,La2/3), Jianjun Liu, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy
Physics Faculty Publications
We have studied the frequency and temperature dependences of permittivity and impedance of the compounds ACu3Ti4O12 A=Ca, Bi2/3, Y2/3, La2/3 in the ranges of 10−1–106 Hz and −150–200 °C. All compounds investigated display similar dielectric properties. Specifically, they all have a Debye-like relaxation and their dielectric constants are independent of frequency and temperature over a wide range. They all have two electrical responses in impedance formalism, indicating that there are two distinct contributions. We attribute them to grains and grain boundaries in the ceramic samples and explain the dielectric behaviors by Maxwell-Wagner relaxation arising at the interfaces between grains and …
Phase Transition In Single Crystal Cs2nb4o11, Jianjun Liu, E. P. Kharitonova, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy
Phase Transition In Single Crystal Cs2nb4o11, Jianjun Liu, E. P. Kharitonova, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy
Physics Faculty Publications
We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs2Nb4O11. First, we observed a sharp λ-shaped peak at 165 °C in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to a structural change from the room temperature orthorhombic Pnn2 to another orthorhombic Imm2. We also measured room temperature polarized Raman spectra in different symmetries of normal vibrations and assigned high wavenumber Raman bands to the …