Chaotic dynamics of electric-field domains in periodically driven superlattices

Universidad Carlos III de Madrid, Escuela Polit´ecnica Superior, Butarque 15, 28911 Legan´es, Spain(11 October 1995)Self-sustained time-dependent current oscillations under dc voltage bias have been observedin recent experiments on n-doped semiconductor superlattices with sequential resonant tunneling.The current oscillations are caused by the motion and recycling of the domain wall separatinglow- and high-electric-field regions of the superlattice, as the analysis of a discrete drift modelshows and experimental evidence supports. Numerical simulation shows that different nonlineardynamical regimes of the domain wall appear when an external microwave signal is superimposedon the dc bias and its driving frequency and driving amplitude vary. On the frequency – amplitudeparameter plane, there are regions of entrainment and quasiperiodicity forming Arnol’d tongues.Chaos is demonstrated to appear at the boundaries of the tongues and in the regions where theyoverlap. Coexistence of up to four electric-field domains randomly nucleated in space is detectedunder ac+dc driving.PACS numbers: 73.20.Dx, 73.40.Gk, 47.52.+jI. INTRODUCTION