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We report the electrical transport in vertical Josephson tunnel junctions (area 400 $\mu m$$^2$) using GdBa$_2$Cu$_3$O$_7$$_{-\delta}$ electrodes and SrTiO$_3$ as an insulating barrier (with thicknesses between 1 nm and 4 nm). The results…

Superconductivity · Physics 2019-12-19 H. Navarro , M. Sirena , N. Haberkorn

We present a strategy for increasing thermoelectric performance by invoking ferroelectric distortion in a transition-metal oxide. By using an ab initio calculation approach with the Boltzmann transport equation, a large Seebeck coefficient…

Materials Science · Physics 2015-06-23 Hiroaki Saijo , Kunihiko Yamauchi , Koun Shirai , Tamio Oguchi

We investigated the relationship between the tunnel magnetoresistance (TMR) ratio and the electrode structure in MgO-barrier magnetic tunnel junctions (MTJs). The TMR ratio in a MTJ with Co40Fe40B20 reference and free layers reached 355% at…

Materials Science · Physics 2015-06-25 Shoji Ikeda , Jun Hayakawa , Young Min Lee , Fumihiro Matsukura , Hideo Ohno

We calculate the tunneling magnetoresistance (TMR) of Fe|ZnSe|Fe|ZnSe|Fe (001) double magnetic tunnel junctions as a function of the in-between Fe layer's thickness, and compare these results with those of Fe|ZnSe|Fe simple junctions. The…

Materials Science · Physics 2013-05-29 Jeronimo Peralta Ramos , Ana Maria Llois

Employing an ab initio Screened Korringa-Kohn-Rostoker (SKKR) band structure method for a metal-vacuum-metal junction, we find that the tunnel conductance is different when it is calculated across the barrier and far from it. We attribute…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. M. Levy , K. Wang , P. H. Dederichs , C. Heide , S. Zhang , L. Szunyogh , P. Weinberger

It has been reported in experiments that capping layers which enhance the perpendicular magnetic anisotropy (PMA) of magnetic tunnel junctions (MTJs) induce great impact on the tunnel magnetoresistance (TMR). To explore the essential…

Computational Physics · Physics 2017-01-02 Jiaqi Zhou , Weisheng Zhao , Yin Wang , Shouzhong Peng , Junfeng Qiao , Li Su , Lang Zeng , Na Lei , Lei Liu , Youguang Zhang , Arnaud Bournel

Van der Waals (vdW) heterostructures have opened new opportunities to develop atomically thin (opto)electronic devices with a wide range of functionalities. The recent focus on manipulating the interlayer twist angle has led to the…

Large efforts in improving thermoelectric energy conversion are devoted to energy filtering by nanometer size potential barriers. In this work we perform an analysis and optimization of such barriers for improved energy filtering. We merge…

Materials Science · Physics 2013-08-01 Neophytos Neophytou , Hans Kosina

The tunnel current and magnetoresistance (TMR) are investigated in magnetic tunnel junctions consisting of a spin-filter tunnel barrier, sandwiched between a ferromagnetic (FM) electrode and a nonmagnetic (NM) electrode. The investigations…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Alireza Saffarzadeh

Perpendicular magnetic tunnel junctions (MTJ) with a bottom pinned reference layer and a composite free layer (FL) are investigated. Different thicknesses of the FL were tested to obtain an optimal balance between tunneling…

We calculate the conductances and the tunneling magnetoresistance (TMR) of double magnetic tunnel junctions, taking as a model example junctions composed of Fe/ZnSe/Fe/ZnSe/Fe (001). The calculations are done as a function of the gate…

Mesoscale and Nanoscale Physics · Physics 2008-09-08 J. Peralta-Ramos , A. M. Llois

The 'Brillouin zone spin filtering' mechanism of enhanced tunneling magnetoresistance (TMR) is described for magnetic tunnel junctions (MTJ) and studied on an example of the MTJ with hcp Co electrodes and hexagonal BN (h-BN) spacer. Our…

Materials Science · Physics 2015-12-16 Sergey V. Faleev , Stuart S. P. Parkin , Oleg N. Mryasov

In the ferrimagnetic semiconductor Mn$_3$Si$_2$Te$_6$, a colossal magnetoresistance (CMR) is observed only when a magnetic field is applied along the magnetic hard axis ($\mathbf{H}\parallel c$). This phenomenon suggests an unconventional…

Density functional plus dynamical mean field calculations are used to show that in transition metal oxides, rotational and tilting (GdFeO$_3$-type) distortions of the ideal cubic perovskite structure produce a multiplicity of low-energy…

Strongly Correlated Electrons · Physics 2015-09-08 Hung T. Dang , Jernej Mravlje , Antoine Georges , Andrew J. Millis

We have carried out calculations of current-voltage characteristics for the electron tunnel current through a junction with a thin insulating ferroelectric barrier assuming that interface transmissions for the left and right interfaces…

Materials Science · Physics 2010-01-05 Natalya A. Zimbovskaya

Precisely engineered tunnel junctions exhibit a long sought effect that occurs when the energy of the electron is comparable to the potential energy of the tunneling barrier. The resistance of metal-insulator-metal tunnel junctions…

Materials Science · Physics 2007-09-25 Casey W. Miller , Zhi-Pan Li , Ivan K. Schuller , R. W. Dave , J. M. Slaughter , Johan Akerman

Though the Fermi surface of surface states of a 3D topological insulator (TI) has zero magnetization, an arbitrary segment of the full Fermi surface has a unique magnetic moment consistent with the type of spin-momentum locking in hand. We…

Mesoscale and Nanoscale Physics · Physics 2015-01-13 Sthitadhi Roy , Abhiram Soori , Sourin Das

Non-equilibrium spin-dependent transport in magnetic tunnel junctions comprising a ferroelectric barrier is theoretically investigated. The exact solutions of the free electron Schr\"odinger equation for electron tunneling in the presence…

Mesoscale and Nanoscale Physics · Physics 2012-11-20 A. Useinov , A. Manchon

We investigate the functionality of the $\mathrm{Cr}$-doped $\mathrm{RuO_{2}}$ as an electrode of the magnetic tunnel junction (MTJ), motivated by the recent experiment showing that $\mathrm{Cr}$-doping into the rutile-type…

Mesoscale and Nanoscale Physics · Physics 2024-10-28 Katsuhiro Tanaka , Takuya Nomoto , Ryotaro Arita

Finite length of a one channel wire results in crossover from a Tomonaga-Luttinger to Fermi liquid behavior with lowering energy scale. In condition that voltage drop $(V)$ mostly occurs across a tunnel barrier inside the wire we found…

Condensed Matter · Physics 2009-10-30 Vadim Ponomarenko , Naoto Nagaosa