Transversely Driven Charge Density Waves: The Current Effect Transistor

We study charge density waves (CDW's) in the presence of a normal (single-particle) current density $J_x$ transverse to the ordering wavevector $2{k_F}{\bf\hat{z}}$ below and above the CDW longitudinal depinning transition. We demonstrate that even for stationary CDW's (below the depinning transition) the transverse current radically alters the long distance correlations. This has many dramatic consequences for experiments: above a ``critical'' transverse normal current $J_c$, the CDW correlation length grows exponentially with $J_x$ as $\xi_L(J_x>J_c)=\xi_L e^{(J_x-J_c)/J_c}$ and concomitantly the CDW depinning electric field decays exponentially with $J_x$. For $J_x>J_c$, the high longitudinal current I-V is qualitatively modified, exhibiting an intermediate linear regime. We propose a novel ``Current Effect Transistor'', in which the CDW channel transport is turned on by a transverse normal current.