Papers by Seif Dhia Alwan
arXiv (Cornell University), Nov 11, 2022
We detail here some matters arising from the recent paper by Qin et al., Nature 606, pages902-908... more We detail here some matters arising from the recent paper by Qin et al., Nature 606, pages902-908 (2022). We demonstrate, based on data supplied by Qian et al, and corroborated by theoretical modeling, that one of the central conclusions of the manuscript-namely the behavior of the chiralityinduced spin-selectivity (CISS) effect at low temperatures-can actually be consistently interpreted in a different way, which is in fact opposite to the interpretation proposed by Qian et al.
When electrons are injected through a chiral molecule, the resulting current may become spin pola... more When electrons are injected through a chiral molecule, the resulting current may become spin polarized. This effect, known as the chirality-induced spin-selectivity (CISS) effect, has been suggested to emerge due to the interplay between spin-orbit interactions and the chirality within the molecule. However, such explanations require unrealistically large values for the molecular spin-orbit interaction. Here, we present a theory for the CISS effect based on the interplay between spin-orbit interactions in the electrode, the chirality of the molecule (which induces a solenoid field), and spin-transfer torque at the molecule-electrode interface. Using a mean-field calculation with simple models for the molecular junction, we show that our phenomenological theory can qualitatively account for all key experimental observations, most importantly the magnitude of the CISS with realistic parameters. We also provide a set of predictions which can be readily tested experimentally.
We investigate the electronic transport through a double quantum dot device embedded in the tunne... more We investigate the electronic transport through a double quantum dot device embedded in the tunnel junction between two metallic leads. We find that transitioning from the serial to the parallel configurations is associated with the progressive reduction of tunneling through one quantum dot. As a result the asymmetric Fano lineshape appears, which we interpret as the formation of an anti-bonding and a bonding state in the junction. The bonding state facilitates the majority of the tunneling as the geometry approaches symmetric coupling to the leads. At the limit of the transition towards the parallel configuration, the anti-bonding state is completely localized from the continuum of the leads and only the bonding state is left to participate in the transmission.
In this work, we investigate electronic transport through a double quantum dot junction, where ea... more In this work, we investigate electronic transport through a double quantum dot junction, where each dot couple to external localized spins. The junction is embedded in between two metallic leads, functioning as continues electron reservoirs. The double quantum dot junction forms in the junction a bonding and anti-bonding state, much resembling the electronic structure of a molecule, hence provides insight to such systems. Due to the nature of the parallel coupling we expect a reduced tunneling through the anti-bonding state as a result of destructive interference as the tunneling is provided multiple pathways through the molecule. We predict that signature effects arise correlating the quantum observable to the effective exchange coupling between the localized spin moment and the electronic structure of the DQD. We expect the Fano resonance to disappear entirely when the anti-bonding state is localized and the transmission is carried purely through the bonding state. We further inve...
The Journal of Chemical Physics
Paper published as part of the special topic on Oxide Chemistry and Catalysis Note: This paper is... more Paper published as part of the special topic on Oxide Chemistry and Catalysis Note: This paper is part of the JCP Special Topic on Oxide Chemistry and Catalysis.
The Journal of Chemical Physics, Mar 14, 2020
Paper published as part of the special topic on Oxide Chemistry and Catalysis Note: This paper is... more Paper published as part of the special topic on Oxide Chemistry and Catalysis Note: This paper is part of the JCP Special Topic on Oxide Chemistry and Catalysis.
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Papers by Seif Dhia Alwan