Chen D et al.Cai SHsu N.-WHuang S.-HChuang YNielsen EJIUN-YUN LICHEE-WEE LIULu T.MLaroche D.2022-04-252022-04-25202100036951https://www.scopus.com/inward/record.uri?eid=2-s2.0-85120411868&doi=10.1063%2f5.0068538&partnerID=40&md5=fabb17e60f2a02559f02b25387c1d05fhttps://scholars.lib.ntu.edu.tw/handle/123456789/606965We report low-temperature magneto-transport measurements of an undoped Si/SiGe asymmetric double quantum well heterostructure. The density in both layers is tuned independently utilizing top and bottom gates, allowing the investigation of quantum wells at both imbalanced and matched densities. Integer quantum Hall states at total filling factor ν T = 1 and ν T = 2 are observed in both density regimes, and the evolution of their excitation gaps is reported as a function of the density. The ν T = 1 gap evolution departs from the behavior generally observed for valley splitting in the single layer regime. Furthermore, by comparing the ν T = 2 gap to the single particle tunneling energy, Δ SAS, obtained from Schr?dinger-Poisson (SP) simulations, evidence for the onset of spontaneous interlayer coherence is observed for a relative filling fraction imbalance smaller than ? 50 %. ? 2021 Author(s).Quantum chemistryQuantum theorySiliconTemperatureAsymmetric double quantum wellsBottom gateDensity dependenceDouble quantum well heterostructuresExcitation gapsLows-temperaturesMagneto-transport measurementMeasurements ofSi/SiGeTop gateSemiconductor quantum wellsjournal article10.1063/5.00685382-s2.0-85120411868