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Two-dimensional (2D) van der Waals (vdW) multiferroic tunnel junctions (MFTJs) composed of a ferromagnetic metal and a ferroelectric barrier have controllable thickness and clean interface and can realize the coexistence of tunneling magnetoresistance (TMR) and tunneling electroresistance (TER). Therefore, they have enormous potential application in nonvolatile multistate memories. Here, using first principles combined with non-equilibrium Green's function method, we have systematically investigated the spin-dependent transport properties of Fe3GeTe2/MnSe/Fe3GeTe2 vdW MFTJs with various numbers of barrier layers. By controlling the polarization orientation of the ferroelectric barrier MnSe and the magnetization alignment of the ferromagnetic electrodes Fe3GeTe2, the MnSe-based MFTJs exhibit four nonvolatile resistance states, with the TMR (TER) becoming higher and reaching a maximum of 1.4 × 106% (4114%) as the MnSe layers increase from a bilayer to a tetralayer. Using asymmetric Cu and Fe3GeTe2 as the electrodes, the TER can be further improved from 349% to 618%. Moreover, there is a perfect spin filtering effect in these MFTJs. This work demonstrates the potential applications of MnSe-based devices in multistate nonvolatile memories and spin filters, which will stimulate experimental studies on layer-controllable spintronic devices. [ABSTRACT FROM AUTHOR]

We design isolated molecular nanowires composed of thiophene oligomers sandwiched between two one-dimensional gold electrodes. Electronic transport through the molecular junctions with two interface geometries is studied by performing the first principles calculations based on density functional theory and nonequilibrium Green's function. The current-voltage (I-V) curves of the molecular wires display an unexpected negative differential resistance and rectifying behaviors along with the oscillation effects, different from other theoretical and experimental studies about the analogous thiophene devices. The significant difference is attributed to the design of the one-dimensional gold electrodes with large enough vacuum layer in transverse direction in order to suppress the interaction between wires. Such transport behaviors indicate that the thiophene molecular device would be an important candidate in future molecular electronics. [ABSTRACT FROM AUTHOR]

In this paper, the electronic and magnetic properties of the Zr2VGa (111), (001), and (110) surfaces are studied via the first-principles calculations based on the density-functional theory. The calculations indicate that the Zr2VGa full-Heusler alloy displays a half-metallic behavior with a total spin magnetic moment of 2.0 μB at the equilibrium lattice parameter of 6.657 Ǻ. The energy band gap is 0.28 eV at the Fermi level. A weak relaxation at the terminations of the (111) and (001) surfaces is obtained which means that the terminations are stable. However, the stronger relaxations are at the terminations of the (110) surface. Examining the electronic density of states, the half-metallicity is determined which was verified in the bulk Zr2VGa and it is destroyed at the (111), (001) and (110) surfaces. Furthermore, it is discovered that the atomic spin magnetic moments at the Zr(2)Ga-terminated (001) surface is decreased compared to those of the bulk Zr2VGa, while the magnetic moments are increased at the Zr(1) and V-terminated (111) surfaces. [ABSTRACT FROM AUTHOR]