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تسجيل مستخدم جديدThe Aharonov-Bohm-Casher ring-dot as a flux-tunable resonant tunneling diode
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A mesoscopic ring subject to the Rashba spin-orbit interaction and sequentially coupled to an interacting quantum dot, in the presence of Aharonov-Bohm flux, is proposed as a flux tunable tunneling diode. The analysis of the conductance by means of the nonequilibrium Greens function technique, shows an intrinsic bistability at varying the Aharonov-Bohm flux when 2U > pi Gamma, U being the charging energy on the dot and Gamma the effective resonance width. The bistability properties are discussed in connection with spin-switch effects and logical storage device applications.
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re than 50% modulation are observed in the conductance. The tuning via in-plane gates allows to study the Aharonov-Bohm effect in the whole range from the open ring to the Coulomb-blockade regime.
We suggest a system in which the amplitude of macroscopic flux tunneling can be modulated via the Aharonov-Casher effect. The system is an rf-SQUID with the Josephson junction replaced by a Bloch transistor -- two junctions separated by a small super
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The Josephson current through an Aharonov-Bohm (AB) interferometer, in which a quantum dot (QD) is situated on one arm and a magnetic flux $Phi$ threads through the ring, has been investigated. With the existence of the magnetic flux, the relation of
the Josephson current and the superconductor phase is complex, and the system can be adjusted to $pi$ junction by either modulating the magnetic flux or the QDs energy level $varepsilon_d$. Due to the electron-hole symmetry, the Josephson current $I$ has the property $I(varepsilon_d,Phi)=I(-varepsilon_d,Phi+pi)$. The Josephson current exhibits a jump when a pair of Andreev bound states aligns with the Fermi energy. The condition for the current jump is given. In particularly, we find that the position of the current jump and the position of the maximum value of the critical current $I_c$ are identical. Due to the interference between the two paths, the critical current $I_c$ versus the QDs level $varepsilon_d$ shows a typical Fano shape, which is similar to the Fano effect in the corresponding normal device. But they also show some differences. For example, the critical current never reaches zero for any parameters, while the current in the normal device can reach zero at the destruction point.
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