Quantum Transport in Black Phosphorus Two-dimensional Electron Gas
Two-dimensional (2D) crystals have emerged as a new class of materials with diverse electronic properties. This is best exemplified by graphene, and more recently by transition metal dichalcogenides. We have recently discovered that a new 2D material, black phosphorus (BP), can host high quality 2D electron system (2DES) with carrier mobility up to 10,000 cm2/Vs at low temperatures. The high mobility enables us to explore the quantum transport in the new 2DES. In particular, we have observed, for the first time, quantum oscillations and more recently integer quantum Hall effect in BP. Heavy carrier mass and strong in-plane anisotropy are two distinct features of the BP 2DES. We observed enhanced electron-electron (e-e) interaction in BP 2DES as a result of the heavy carrier mass, and new states emerging at fractional filling factors possibly due to the anisotropic e-e interaction.