Controlling Interactions between Mn Acceptors in the GaAs (110) Surface

Low temperature scanning tunneling microscopy (STM) is used to control the substitution of individual Mn adatoms into Ga sites in the GaAs (110) surface. In a Ga site, a Mn atom gives rise to a strong in-gap level with highly anisotropic character as probed by spatially-resolved STM spectroscopy measurements. Modifications to this in-gap resonance can occur when two Mn acceptors interact. The interaction of Mn acceptors depends upon both orientation as well as spacing, leading to strong bonding/antibonding-like states under certain configurations. Such measurements of interacting pairs of Mn can potentially provide information on their spin orientation.