title: Dynamical symmetry breaking as the origin of the zero-dc-resistance state in an ac-driven system.
abstract: Under a strong ac drive the zero-frequency linear response dissipative resistivity rho(d)(j=0) of a homogeneous state is allowed to become negative. We show that such a state is absolutely unstable. The only time-independent state of a system with a rho(d)(j=0)<0 is characterized by a current which almost everywhere has a magnitude j(0) fixed by the condition that the nonlinear dissipative resistivity rho(d)(j(2)(0))=0. As a result, the dissipative component of the dc-electric field vanishes. The total current may be varied by rearranging the current pattern appropriately with the dissipative component of the dc-electric field remaining zero. This result, together with the calculation of Durst et al., indicating the existence of regimes of applied ac microwave field and dc magnetic field where rho(d)(j=0)<0, explains the zero-resistance state observed by Mani et al. and Zudov et al.
authors.affiliation: Physics Department, University of Colorado, Boulder, Colorado 80309, USA and Bell Labs, Lucent Technologies, Room 1D-267, Murray Hill, New Jersey 07974, USA.
authors.forename: A V
authors.initials: AV
authors.lastname: Andreev
authors.forename: I L
authors.initials: IL
authors.lastname: Aleiner
authors.forename: A J
authors.initials: AJ
authors.lastname: Millis