Dynamical regime of electron transport in correlated one-dimensional conductor with defect

Abstract

The electron transport in a 1D conductor with an isolated local defect such as an impurity or a non-adiabatic contact is studied theoretically. New regime of conduction in correlated 1D systems is predicted beyond the well-known regime of tunneling resulting in the power-law I-V-curves. In this regime a quantum wire becomes "opened" at voltage biases above the threshold value $V_T$, giving rise to a rapid increase of the dc current, $\bar I$, accompanied by ac oscillations of frequency $f = \bar I/e$. The effect of ac generation is related to sliding of the Friedel oscillations of electronic density produced by the defect. Manifestations of the effect resemble the Coulomb blockade and the Josephson effect. The spin bias applied to the system is shown to affect the I-V curves due to violation of the spin-charge separation at the defect site. In short quantum wires of length $L < L_0 \sim \hbar v_F/eV_T$ and at high temperatures $T > T_0 \sim eV_T/k_B$ the effect is destroyed by fluctuations. The threshold voltage $V_T$ is determined by $2k_F$-component of impurity potential renormalized by fluctuations. The 1D conductor is described in terms of the Tomonaga-Luttinger Hamiltonian with short range or long-range Coulomb interaction by means of the bosonization technique. We derive boundary conditions that take into account relaxation in the leads and permit to solve non-equilibrium problems. Charge fluctuations are studied by means of Gaussian model which can be justified strictly in the limit of large voltages or strong enough inter-electronic repulsion. Spin fluctuations are taken into account strictly by means of the refermionization technique applicable in case of spin-rotation invariant interaction.