Observation of the symmetry of core states of a single Fe impurity in GaAs

TL;DR

This study directly observes and characterizes two distinct mid-gap d-states of a single Fe impurity in GaAs, revealing their symmetry, hybridization, and potential for spin manipulation.

Contribution

It provides the first direct measurement of impurity d-states' symmetry and hybridization in GaAs, supported by tight-binding calculations, advancing understanding of impurity states in semiconductors.

Findings

Two mid-gap Fe d-states with different symmetries observed

One state is strongly localized, the other extended

Measurements agree with tight-binding calculations

Abstract

We report the direct observation of two mid-gap core d-states of differing symmetry for a single Fe atom embedded in GaAs. These states are distinguished by the strength of their hybridization with the surrounding host electronic structure. The mid-gap state of Fe that does not hybridize via sigma-bonding is strongly localized to the Fe atom, whereas the other, which does, is extended and comparable in size to other acceptor states. Tight-binding calculations of these mid-gap states agree with the spatial structure of the measured wave functions, and illustrate that such measurements can determine the degree of hybridization via pi-bonding of impurity d-states. These single-dopant mid-gap states with strong d-character, which are intrinsically spin-orbit-entangled, provide an opportunity for probing and manipulating local magnetism and may be of use for high-speed electrical control of single spins.