Spin and Valley States in Gate-Defined Bilayer Graphene Quantum Dots

In bilayer graphene, electrostatic confinement can be realized by a suitable design of top and back gate electrodes. We measure electronic transport through a bilayer graphene quantum dot, which is laterally confined by gapped regions and connected to the leads via p-n junctions. Single electron and hole occupancy is realized and charge carriers n = 1, 2,...50 can be filled successively into the quantum system with charging energies exceeding 10 meV. For the lowest quantum states, we can clearly observe valley and Zeeman splittings with a spin g-factor of g(s) approximate to 2. In the low-field limit, the valley splitting depends linearly on the perpendicular magnetic field and is in qualitative agreement with calculations.