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A Sachrajda

Publications and source records attributed to A Sachrajda.

3 recordsLinked to original sources

Excitonic energy shell structure of self-assembled InGaAs/GaAs quantum dots.

Performing optical spectroscopy of highly homogeneous quantum dot arrays in ultrahigh magnetic fields, an unprecedently well resolved Fock-Darwin spectrum is observed. The existence of up to four degenerate electronic shells is demonstrated where the magnetic field lifts the initial degeneracies, which reappear when levels with different angular momenta come into resonance. The resulting level shifting and crossing pattern also show evidence of many-body effects such as the mixing of configurations and exciton condensation at the resonances.

Journal Article↗

Collective character of spin excitations in a system of Mn2+ spins coupled to a two-dimensional electron gas.

We have studied the low energy spin excitations in n-type CdMnTe based dilute magnetic semiconductor quantum wells. For magnetic fields for which the energies for the excitation of free carriers and Mn spins are almost identical, an anomalously large Knight shift is observed. Our findings suggest the existence of a magnetic-field-induced ferromagnetic order in these structures, which is in agreement with recent theoretical predictions [Phys. Rev. Lett. 91, 077202 (2003)]].

Journal Article↗