Graphene quantum dots (GQDs) can exhibit a range of spectacular phenomena such as the Klein tunneling induced quasibound states and Berry phase tuned energy spectra. According to previous studies, all these interesting quantum phenomena seem to be well understood in the free electron picture. However, electronic motion in the GQDs is locally reduced to quantized orbits by quantum confinement, which implies that the kinetic energy in the GQDs may be comparable to or even smaller than the Coulomb energy of the quasiparticles, possibly resulting in exotic correlated phases. Here we present a scanning tunneling microscopy and spectroscopy study of gate-tunable GQDs in $\text{graphene}\text{/}{\mathrm{WSe}}_2$ heterostructure devices and report a correlation-induced exotic phase in the GQDs. Gating allows us to precisely characterize effects of the electron-electron interaction on the energy spectra of the GQDs. By measuring density of states as a function of energy and position, we explicitly uncover two density waves with different velocities in the GQDs, attributing to spin-charge separation in real space.

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• Graphene
• Strongly correlated systems
• Scanning tunneling spectroscopy