Individual Cr atom in a semiconductor quantum dot: optical addressability and spin-strain coupling

TL;DR

This paper demonstrates the optical control of a single Chromium atom's spin within a semiconductor quantum dot and explores its strong coupling to local strain, relevant for hybrid spin-mechanical devices.

Contribution

It provides the first demonstration of optical addressability of a single Cr atom's spin in a quantum dot and models its spin-strain interactions.

Findings

Cr-doped quantum dots exhibit large magnetic anisotropy due to local strain.

Zero field splitting of Cr spin states is observed, indicating thermalization on specific ground states.

Strong spin-strain coupling suggests potential for hybrid spin-mechanical systems.

Abstract

We demonstrate the optical addressability of the spin of an individual Chromium atom (Cr) embedded in a semiconductor quantum dot. The emission of Cr-doped quantum dots and their evolution in magnetic field reveal a large magnetic anisotropy of the Cr spin induced by local strain. This results in the zero field splitting of the 0, +-1 and +-2 Cr spin states and in a thermalization on the magnetic ground states 0 and +-1. The observed strong spin to strain coupling of Cr is of particular interest for the development of hybrid spin-mechanical devices where coherent mechanical driving of an individual spin in an oscillator is needed. The magneto-optical properties of Cr-doped quantum dots are modelled by a spin Hamiltonian including the sensitivity of the Cr spin to the strain and the influence of the quantum dot symmetry on the carrier-Cr spin coupling.