Observation of Coulomb repulsion between Cu intercalants in Cu sub(x) Bi sub(2) Se sub(3)

Using scanning tunneling microscopy and ab initio simulations, we have identified several configurations for Cu dopants in Cu sub(x) Bi sub(2) Se sub(3), with Cu intercalants being the most abundant. Through statistical analysis, we show strong short-range repulsive interactions between Cu intercalants. At intermediate range (>5 nm), the pair distribution function shows oscillatory structure along the [left angle bracket]101[right angle bracket] directions, which appear to be influenced by different diffusion barriers along the [left angle bracket]101[right angle bracket] and [left angle bracket]211[right angle bracket] directions.