Quantum Floquet anomalous Hall states and quantized ratchet effect in one-dimensional dimer chain driven by two ac electric fields

摘要

In condensed matter physics, one of the major topics is to find out andclassify interesting novel topological matters and phenomena. Topologicallynontrivial systems can also be achieved by using periodical driving fields. Onthe other hand, ratchet effect can be used to collect useful work fromfluctuations or realize directed transport in periodically-driven systems.Here, we promote a dimer chain by applying two mutually-perpendicular acelectric fields, and obtain an effective two-dimensional Hamiltonian in thelow-frequency regime. We thereby derive quantum Floquet anomalous Hall (QFAH)conductance and then find a quantized ratchet effect in the resulting currentalong the chain. Our further analysis shows that these originate from theelectric fields only. This lengthwise quantized ratchet effect without magneticfield should be useful to designing novel high-performance electronicapplications.