Atom-by-Atom Substitution of Mn in GaAs and Visualization of their Hole-Mediated Interactions

Abstract

The discovery of ferromagnetism in Mn doped GaAs [1] has ignited interest in the development of semiconductor technologies based on electron spin and has led to several proof-of-concept spintronic devices [2-4]. A major hurdle for realistic applications of (Ga,Mn)As, or other dilute magnetic semiconductors, remains their below room-temperature ferromagnetic transition temperature. Enhancing ferromagnetism in semiconductors requires understanding the mechanisms for interaction between magnetic dopants, such as Mn, and identifying the circumstances in which ferromagnetic interactions are maximized [5]. Here we report the use of a novel atom-by-atom substitution technique with the scanning tunnelling microscope (STM) to perform the first controlled atomic scale study of the interactions between isolated Mn acceptors mediated by the electronic states of GaAs. High-resolution STM measurements are used to visualize the GaAs electronic states that participate in the Mn-Mn interaction and to quantify the interaction strengths as a function of relative position and orientation. Our experimental findings, which can be explained using tight-binding model calculations, reveal a strong dependence of ferromagnetic interaction on crystallographic orientation. This anisotropic interaction can potentially be exploited by growing oriented Ga1-xMnxAs structures to enhance the ferromagnetic transition temperature beyond that achieved in randomly doped samples. Our experimental methods also provide a realistic approach to create precise arrangements of single spins as coupled quantum bits for memory or information processing purposes.

References in corpus (4)

• Spatial structure of an individual Mn acceptor in GaAs
• Impurity Band Conduction in a High Temperature Ferromagnetic Semiconductor
• Multiband tight-binding model of local magnetism in GaMnAs
• Spin-orientation-dependent spatial structure of a magnetic acceptor state in a zincblende semiconductor

Cited by in corpus (12)

• Optically probing the fine structure of a single Mn atom in an InAs quantum dot
• Optical Properties of III-Mn-V Ferromagnetic Semiconductors
• Observing Spin Polarization of Individual Magnetic Adatoms
• Onset of ferromagnetism in low-doped GaMnAs
• STM images of sub-surface Mn atoms in GaAs: evidence of hybridization of surface and impurity states
• Single exciton spectroscopy of single-Mn doped InAs quantum dots
• Mapping the wavefunction of transition metal acceptor states in the GaAs surface
• Magnetic circular dichroism from the impurity band in III-V diluted magnetic semiconductors
• Exploiting B Site Disorder for Phase Control in the Manganites
• Ferromagnetism in transparent Mn(II)-doped indium tin oxide films prepared by sol-gel process
• Inter-impurity and impurity-host magnetic correlations in semiconductors with low-density transition-metal impurities
• Perspectives in spintronics: magnetic resonant tunneling, spin-orbit coupling, and GaMnAs