论文标题
INAS纳米线和石墨烯异质结构之间的异常库仑在
Anomalous Coulomb Drag between InAs Nanowire and Graphene Heterostructures
论文作者
论文摘要
相关电荷不均匀性破坏了二维(2D)双层异质结构中的电子孔对称性,该异质结构负责在电荷中立点出现非零阻力。在这里,我们报告了新型阻力系统中的库仑阻力,由二维石墨烯和一个尺寸(1D)INAS纳米线(NW)异质结构,其表现出来自2D-2D异质结构的明显结果。对于单层石墨烯(MLG)-NW异质结构,由于相关的层间电荷水坑,我们观察到越野点附近的非常规的阻力峰。阻力信号随温度($ \ sim t^{ - 2} $)和NW的载体密度($ \ sim n_ {n}^{ - 4} $)而单调降低,但是随着磁场($ \ sim b^{2} $)而迅速增加。这些异常响应以及石墨烯和NWS的不匹配的导热率,将能量阻力确立为MLG-NW设备中库仑阻力的负责机理。相反,对于双层石墨烯(BLG)-NW设备,阻力电阻会逆转越野点的符号,而阻力信号的大小随NW的载体密度而降低($ \ sim n_ {n_ {n}^{-1.5} $),与动力拖动保持一致,但与磁场和温度保持恒定。与预期的$ t^2 $的这种偏差是由于石墨烯载体密度上的阻力最大值的变化而产生的。我们还表明,在BLG-NW设备中观察到Onsager互惠关系,但对于MLG-NW设备而言未观察到。迄今未报告的这些库仑阻力测量结果(2d-1d)系统将铺平新系统中相关冷凝水状态的未来实现。
Correlated charge inhomogeneity breaks the electron-hole symmetry in two-dimensional (2D) bilayer heterostructures which is responsible for non-zero drag appearing at the charge neutrality point. Here we report Coulomb drag in novel drag systems consisting of a two-dimensional graphene and a one dimensional (1D) InAs nanowire (NW) heterostructure exhibiting distinct results from 2D-2D heterostructures. For monolayer graphene (MLG)-NW heterostructures, we observe an unconventional drag resistance peak near the Dirac point due to the correlated inter-layer charge puddles. The drag signal decreases monotonically with temperature ($\sim T^{-2}$) and with the carrier density of NW ($\sim n_{N}^{-4}$), but increases rapidly with magnetic field ($\sim B^{2}$). These anomalous responses, together with the mismatched thermal conductivities of graphene and NWs, establish the energy drag as the responsible mechanism of Coulomb drag in MLG-NW devices. In contrast, for bilayer graphene (BLG)-NW devices the drag resistance reverses sign across the Dirac point and the magnitude of the drag signal decreases with the carrier density of the NW ($\sim n_{N}^{-1.5}$), consistent with the momentum drag but remains almost constant with magnetic field and temperature. This deviation from the expected $T^2$ arises due to the shift of the drag maximum on graphene carrier density. We also show that the Onsager reciprocity relation is observed for the BLG-NW devices but not for the MLG-NW devices. These Coulomb drag measurements in dimensionally mismatched (2D-1D) systems, hitherto not reported, will pave the future realization of correlated condensate states in novel systems.