Hand Zenia | University Abderahmane Mira, Bejaia (original) (raw)
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Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect ... more Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect forces any finite number of "barrier" planes that are described by the (paramagnetic) Hubbard model and sandwiched between semi-infinite metallic leads to always be a Fermi liquid at T=0. This then implies that the inhomogeneous system restores lattice periodicity at zero frequency, has a well-defined Fermi surface, and should display perfect (ballistic) conductivity or "transparency". These results are, however, fragile with respect to finite frequency, V, T, disorder, or magnetism, all of which restore the expected quantum tunneling regime through a finite-width Mott insulator. Our formal results are complemented by numerical renormalization group studies on small thickness barriers that illustrate under what circumstances this behavior might be seen in real experimental systems.
Self-consistent inhomogeneous DMFT calculations as well as analytical investigations of the elect... more Self-consistent inhomogeneous DMFT calculations as well as analytical investigations of the electronic structure of a multilayered device are presented. The device consists of two semi-infinite leads of a ballistic metal that sandwich an interacting barrier. The interactions in the barrier are described by the Hubbard model with the whole system particle-hole symmetric. We find that for a finite barrier no matter how strong the interaction, the system becomes a Fermi liquid with a perfect metallic conductivity at low enough temperature. We argue that at zero temperature and frequency the Luttinger theorem holds and that the system has a well defined Fermi surface. The perfect conducting state may be extremely fragile to finite temperature, finite driving electric fields, finite driving frequencies, or disorder, so it will often be difficult to see experimentally. We will discuss possible experimental realizations of the phenomena
Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect ... more Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect forces any finite number of "barrier" planes that are described by the (paramagnetic) Hubbard model and sandwiched between semi-infinite metallic leads to always be a Fermi liquid at T=0. This then implies that the inhomogeneous system restores lattice periodicity at zero frequency, has a well-defined Fermi surface, and should display perfect (ballistic) conductivity or "transparency". These results are, however, fragile with respect to finite frequency, V, T, disorder, or magnetism, all of which restore the expected quantum tunneling regime through a finite-width Mott insulator. Our formal results are complemented by numerical renormalization group studies on small thickness barriers that illustrate under what circumstances this behavior might be seen in real experimental systems.
We present results of first principles calculations of the electronic and magnetic properties of ... more We present results of first principles calculations of the electronic and magnetic properties of the La0.7Sr0.3MnO3/SrTiO3 interface. We are interested in the changes with respect to the bulk as concerns ferromagnetism and half-metallicity. The bulk calculations give a nearly half-metallic ground state for the manganite. In transport the system is predicted to be totally half-metallic. This latter property is preserved at the interface only if the magnetic coupling between the interface region and the bulk is ferromagnetic. We have looked at the two possible interface terminations between La0.7Sr0.3MnO3 and SrTiO3 and found that one of the interfaces preserves the bulk properties of La0.7Sr0.3MnO3 whereas the other type of termination suppresses them. Reducing the number of holes at the interface by introducing LaMnO3 restores ferromagnetism. Hence the possibility of engineering interfaces to improve the Tunneling Magneto-Resistance yield in the La0.7Sr0.3MnO3/SrTiO3/La0.7Sr0.3MnO3 tunnel junctions.
Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect ... more Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect forces any finite number of "barrier" planes that are described by the (paramagnetic) Hubbard model and sandwiched between semi-infinite metallic leads to always be a Fermi liquid at T=0. This then implies that the inhomogeneous system restores lattice periodicity at zero frequency, has a well-defined Fermi surface, and should display perfect (ballistic) conductivity or "transparency". These results are, however, fragile with respect to finite frequency, V, T, disorder, or magnetism, all of which restore the expected quantum tunneling regime through a finite-width Mott insulator. Our formal results are complemented by numerical renormalization group studies on small thickness barriers that illustrate under what circumstances this behavior might be seen in real experimental systems.
Self-consistent inhomogeneous DMFT calculations as well as analytical investigations of the elect... more Self-consistent inhomogeneous DMFT calculations as well as analytical investigations of the electronic structure of a multilayered device are presented. The device consists of two semi-infinite leads of a ballistic metal that sandwich an interacting barrier. The interactions in the barrier are described by the Hubbard model with the whole system particle-hole symmetric. We find that for a finite barrier no matter how strong the interaction, the system becomes a Fermi liquid with a perfect metallic conductivity at low enough temperature. We argue that at zero temperature and frequency the Luttinger theorem holds and that the system has a well defined Fermi surface. The perfect conducting state may be extremely fragile to finite temperature, finite driving electric fields, finite driving frequencies, or disorder, so it will often be difficult to see experimentally. We will discuss possible experimental realizations of the phenomena
Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect ... more Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect forces any finite number of "barrier" planes that are described by the (paramagnetic) Hubbard model and sandwiched between semi-infinite metallic leads to always be a Fermi liquid at T=0. This then implies that the inhomogeneous system restores lattice periodicity at zero frequency, has a well-defined Fermi surface, and should display perfect (ballistic) conductivity or "transparency". These results are, however, fragile with respect to finite frequency, V, T, disorder, or magnetism, all of which restore the expected quantum tunneling regime through a finite-width Mott insulator. Our formal results are complemented by numerical renormalization group studies on small thickness barriers that illustrate under what circumstances this behavior might be seen in real experimental systems.
We present results of first principles calculations of the electronic and magnetic properties of ... more We present results of first principles calculations of the electronic and magnetic properties of the La0.7Sr0.3MnO3/SrTiO3 interface. We are interested in the changes with respect to the bulk as concerns ferromagnetism and half-metallicity. The bulk calculations give a nearly half-metallic ground state for the manganite. In transport the system is predicted to be totally half-metallic. This latter property is preserved at the interface only if the magnetic coupling between the interface region and the bulk is ferromagnetic. We have looked at the two possible interface terminations between La0.7Sr0.3MnO3 and SrTiO3 and found that one of the interfaces preserves the bulk properties of La0.7Sr0.3MnO3 whereas the other type of termination suppresses them. Reducing the number of holes at the interface by introducing LaMnO3 restores ferromagnetism. Hence the possibility of engineering interfaces to improve the Tunneling Magneto-Resistance yield in the La0.7Sr0.3MnO3/SrTiO3/La0.7Sr0.3MnO3 tunnel junctions.