Magnetic properties of substitutional Mn in (110) GaAs surface and subsurface layers

TL;DR

This study theoretically investigates the electronic and magnetic properties of substitutional Mn in (110) GaAs surfaces, revealing how the acceptor wave function and magnetic anisotropy depend on Mn depth and orientation.

Contribution

It provides a detailed theoretical analysis of Mn-induced acceptor levels in GaAs surfaces, incorporating surface relaxation effects and depth-dependent magnetic anisotropy.

Findings

Acceptor wave function is highly anisotropic and depth-dependent.

LDOS sensitivity to Mn magnetic moment orientation increases with depth.

Magnetic anisotropy energy is mainly due to acceptor level energy dependence.

Abstract

Motivated by recent STM experiments, we present a theoretical study of the electronic and magnetic properties of the Mn-induced acceptor level obtained by substituting a single Ga atom in the (110) surface layer of GaAs or in one of the atoms layers below the surface. We employ a kinetic-exchange tight-binding model in which the relaxation of the (110) surface is taken into account. The acceptor wave function is strongly anisotropic in space and its detailed features depend on the depth of the sublayer in which the Mn atom is located. The local-density-of-states (LDOS) on the (110) surface associated with the acceptor level is more sensitive to the direction of the Mn magnetic moment when the Mn atom is located further below the surface. We show that the total magnetic anisotropy energy of the system is due almost entirely to the dependence of the acceptor level energy on Mn spin orientation, and that this quantity is strongly dependent on the depth of the Mn atom.