Keren Itai, Dvir Tom, Zalic Ayelet, Iluz Amir, LeBoeuf David, Watanabe Kenji, Taniguchi Takashi, Steinberg Hadar
Racah Institute of Physics, The Hebrew University, 91904, Jerusalem, Israel.
LNCMI, Centre National de la Recherche Scientifique, EMFL, Université Grenoble Alpes, INSA Toulouse, Université Toulouse Paul Sabatier, Grenoble, France.
Nat Commun. 2020 Jul 8;11(1):3408. doi: 10.1038/s41467-020-17225-1.
Energy spectroscopy of strongly interacting phases requires probes which minimize screening while retaining spectral resolution and local sensitivity. Here, we demonstrate that such probes can be realized using atomic sized quantum dots bound to defects in hexagonal Boron Nitride tunnel barriers, placed at nanometric distance from graphene. With dot energies capacitively tuned by a planar graphite electrode, dot-assisted tunneling becomes highly sensitive to the graphene excitation spectrum. The spectra track the onset of degeneracy lifting with magnetic field at the ground state, and at unoccupied excited states, revealing symmetry-broken gaps which develop steeply with magnetic field - corresponding to Landé g factors as high as 160. Measured up to B = 33 T, spectra exhibit a primary energy split between spin-polarized excited states, and a secondary spin-dependent valley-split. Our results show that defect dots probe the spectra while minimizing local screening, and are thus exceptionally sensitive to interacting states.
强相互作用相的能谱需要在保持光谱分辨率和局部灵敏度的同时，将屏蔽效应降至最低的探针。在此，我们证明了可以通过将原子尺寸的量子点与六方氮化硼隧道势垒中的缺陷相结合来实现这样的探针，这些量子点与石墨烯的距离为纳米级。通过平面石墨电极电容性地调节量子点的能量，量子点辅助隧穿对石墨烯激发光谱变得高度敏感。光谱跟踪了基态和未占据激发态下磁场导致的简并解除的起始情况，揭示了随着磁场急剧发展的对称性破缺能隙——对应高达160的朗德g因子。在高达B = 33 T的磁场下测量，光谱显示出自旋极化激发态之间的主要能量分裂以及次要的自旋相关谷分裂。我们的结果表明，缺陷量子点在最小化局部屏蔽的同时探测光谱，因此对相互作用态异常敏感。
