Exciton magnetic polarons in the semimagnetic alloysCd1−x−y

Magnetic Polaron Formation in Semimagnetic Semiconductor Heterostructures

“…1). Despite the considerable increase in the polaron equilibrium energy with increasing Mg content, the formation times differ only slightly [24]. Therefore, we conclude that the formation time does not scale with the MP energy and with a degree of the initial localization, but is determined by the relaxation dynamics in the system of Mn ions.…”

Direct Measurements of Magnetic Polarons in Cd1–xMnxSe Nanocrystals from Resonant Photoluminescence

“…These two trends in the resonant PL -namely, the drop in both ∆E and the linewidth as B is increased -are telltale hallmarks of EMPs that have been previously observed in higher-dimensional and rather heavily Mn-doped diluted magnetic semiconductors such as CdMnTe-based epilayers and quantum wells with x >10% [36][37][38]41]. These trends, now clearly observed here in lightly doped but strongly confined 0D nanocrystals, are due to the decrease of the EMP binding energy, and also the decrease of Mn 2+ spin fluctuations, by the applied field B.…”

“…Moreover, the resonant PL linewidth provides immediate insight into Mn 2+ spin fluctuations. Resonant PL methods have been used to quantify EMP energies and spin fluctuations in Mn 2+ -doped semiconductor epilayers [37,42] and quantum wells [36,38,41]. To date, however, this powerful technique has never been applied to study EMPs in colloidal nanocrystals, despite the fact that they represent the strongest case of 0D quantum confinement, in which sp-d exchange is expected to be most enhanced.…”

“…In turn, these aligned local moments act back on the exciton's spin, which lowers the exciton's energy, further localizes the exciton, and further stabilizes the polaron. The stability and binding energy of EMPs therefore depends on the detailed interplay between many factors including the exciton lifetime, the polaron formation time, the exchange field B ex , sample dimensionality, and temperature.EMPs and collective magnetic phenomena have been experimentally studied in a variety of Mn 2+ -doped semiconductor nanostructures, including CdMnSe and CdMnTe-based epilayers and quantum wells [34][35][36][37][38][39][40][41][42], selfassembled CdMnSe and CdMnTe quantum dots grown by molecular-beam epitaxy [14][15][16][18][19][20][21][22][23][24][25], and most recently in CdMnSe nanocrystals synthesized via colloidal techniques [8,28]. Common measurement techniques include the analysis of conventional (i.e., non-resonant) PL [8, 14, 15,18,21,28,39] and time-resolved PL [8, 16,28,34,35,40].…”

Development of CdTe/Cd1-xMgxTe Double Barrier, Single Quantum Well Heterostructures for Resonant Tunneling

“…Recently quantum Hall effect in modulation doped CdTe/CdMgTe single quantum wells has been observed [12], demonstrating that high mobility twodimensional systems can be fabricated. In optical studies the non-magnetic CdMgTe turned out to be the ideal counterpart for the semimagnetic CdMnTe due to its very similar crystalline and electronic properties [13,14]. Thus the quateuary system CdMgMnTe provides the unique possibility to alter separately the electronic and magnetic properties in a heterostructure.…”