Control of single spins in individual magnetic quantum dots

Abstract

The optical properties of individual quantum dots doped with a single Mn atom and charged with a single carrier (electron or hole) are analyzed. Bias controlled single-carrier charging combined with photo depletion is used to control the charge state of individual Mn-doped quantum dots. The emission of the neutral, negatively charged and positively charged excitons coupled with a single magnetic atom are observed in the same quantum dot. The emission pattern of the charged excitons differs strongly from that of the neutral excitons (single and biexciton). This difference reflects the fact that the Mn spin is very sensitive to the number of electrons and holes in both the excited and the ground states of the optical transitions. The spectrum of charged excitons in interaction with the Mn atom shows a rich pattern that can be attributed to a strong anisotropy of the hole -Mn exchange interaction This opens the way of storing information on a single carrier spin on a long time scale in the absence of external magnetic field.

Single Magnetic Impurities in Colloidal Quantum Dots and Magic-Size Clusters

“…Additionally, optical spin orientation of a single magnetic ion in a QD has been demonstrated, , as has optical spin detection . Coherent spin precession of an individual Mn 2+ ion has been demonstrated using pump–probe techniques, and optical pumping and readout of a specific spin state has also been achieved. ,, Although manganese is by far the most thoroughly investigated dopant for SDQD studies, − ,,, individual cobalt, chromium, and iron impurities have also been examined in individual self-assembled QDs, with exciting results from each.…”

Theory of magnetism in diluted magnetic semiconductor nanocrystals

“…[1][2][3][4] Moreover, recent technical advances have made it possible to incorporate controlled number of magnetic ions, typically Mn 2+ , into individual colloidal semiconductor nanocrystals [5][6][7][8] and selfassembled quantum dots. [9][10][11][12][13] Rich physical phenomena, such as giant Zeeman splitting, 14 magnetic polarons, 13,15,16 zerofield magnetization, [17][18][19] and rich fine structures of exciton-Mn complexes [9][10][11][12] in those magnetic nanostructures have been observed. The underlying physics of the most physical phenomena can be attributed to the intriguing spin interactions between magnetic ions and quantum confined carriers.…”