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Register a new userTemperature dependence of electron transport through a quantum shuttle
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We analyze electron transport through a quantum shuttle for the applied voltage below the instability threshold. We obtain current-voltage characteristics of this system and show that at low temperature they exhibit pronounced steps. The temperature dependence of the current is calculated in the range from 2K to 300K and it demonstrates a wide variety of behavior - from 1/T decreasing to an exponential growth - depending on how deep the shuttle is in quantum regime. The results obtained are compared to experimental data on electron transport through long molecules.
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The finite-temperature transport properties of FeRh compounds are investigated by first-principles Density Functional Theory-based calculations. The focus is on the behavior of the longitudinal resistivity with rising temperature, which exhibits an abrupt decrease at the metamagnetic transition point, $T = T_m$ between ferro- and antiferromagnetic phases. A detailed electronic structure investigation for $T geq 0$ K explains this feature and demonstrates the important role of (i) the difference of the electronic structure at the Fermi level between the two magnetically ordered states and (ii) the different degree of thermally induced magnetic disorder in the vicinity of $T_m$, giving different contributions to the resistivity. To support these conclusions, we also describe the temperature dependence of the spin-orbit induced anomalous Hall resistivity and Gilbert damping parameter. For the various response quantities considered the impact of thermal lattice vibrations and spin fluctuations on their temperature dependence is investigated in detail. Comparison with corresponding experimental data finds in general a very good agreement.
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Angular momentum transport in magnetic multilayered structures plays a central role in spintronic physics and devices. The angular momentum currents or spin currents are carried by either quasi-particles such as electrons and magnons, or by macroscopic order parameters such as local magnetization of ferromagnets. Based on the generic interface exchange interaction, we develop a microscopic theory that describes interfacial spin conductance for various interfaces among non-magnetic metals, ferromagnetic and antiferromagnetic insulators. Spin conductance and its temperature dependence are obtained for different spin batteries including spin pumping, temperature gradient and spin Hall effect. As an application of our theory, we calculate the spin current in a trilayer made of a ferromagnetic insulator, an antiferromagnetic insulator and a non-magnetic heavy metal. The calculated results on the temperature dependence of spin conductance quantitatively agree with the existing experiments.
Contents: (1) Model of a lateral quantum dot system (2) Thermally-activated conduction: onset of the Coulomb blockade oscillations and Coulomb blockade peaks at low temperature (3) Activationless transport through a blockaded quantum dot: inelastic and elastic co-tunneling (4) Kondo regime in transport through a quantum dot: effective low-energy Hamiltonian; linear response; weak coupling regime; strong coupling regime; beyond linear response; splitting of the Kondo peak in a magnetic field; Kondo effect in quantum dots with large spin.
Organic multiferroic tunnel junctions (OMFTJs) with multi-resistance states have been proposed and drawn intensive interests due to their potential applications, for examples of memristor and spintronics based synapse devices. The ferroelectric control of spin-polarization at ferromagnet (FM)/ferroelectric organic (FE-Org) interface by electrically switching the ferroelectric polarization of the FE-Org has been recently realized. However, there is still a lack of understanding of the transport properties in OMFTJs, especially the interplay between the ferroelectric domain structure in the organic barrier and the spin-polarized electron tunneling through the barrier. Here, we report on a systematic study of the temperature dependent transport behavior in La0.6Sr0.4MnO3/PVDF/Co OMFTJs. It is found that the thermal fluctuation of the ferroelectric domains plays an important role on the transport properties. When T>120K, the opposite temperature dependence of resistance for in up and down ferroelectric polarization states results in a rapid diminishing of tunneling electroresistance (TER). These results contribute to the understanding of the transport properties for designing high performance OMFTJs for memristor and spintronics applications.
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