arXiv subjects

Igor Žutić

Publications and source records attributed to Igor Žutić.

58 records · Page 4Linked to original sources

arXiv2012

Reentrant Formation of Magnetic Polarons in Quantum Dots

We propose a model of magnetic polaron formation in semiconductor quantum dots doped with magnetic ions. A wetting layer serves as a reservoir of photo-generated holes, which can be trapped by the adjacent quantum dots. For certain hole densities, the temperature dependence of the magnetization induced by the trapped holes is reentrant: it disappears for some temperature range and reappears at higher temperatures. We demonstrate that this peculiar effect is not an artifact of the mean field approximation and persists after statistical spin fluctuations are accounted for. We predict fingerprints of reentrant magnetic polarons in photoluminescence spectra.

cond-mat.mes-hall↗

arXiv2012

Spin-orbit coupled particle in a spin bath

We consider a spin-orbit coupled particle confined in a quantum dot in a bath of impurity spins. We investigate the consequences of spin-orbit coupling on the interactions that the particle mediates in the spin bath. We show that in the presence of spin-orbit coupling, the impurity-impurity interactions are no longer spin-conserving. We quantify the degree of this symmetry breaking and show how it relates to the spin-orbit coupling strength. We identify several ways how the impurity ensemble can in this way relax its spin by coupling to phonons. A typical resulting relaxation rate for a self-assembled Mn-doped ZnTe quantum dot populated by a hole is 1 $μ$s. We also show that decoherence arising from nuclear spins in lateral quantum dots is still removable by a spin echo protocol, even if the confined electron is spin-orbit coupled.

cond-mat.mes-hall↗

arXiv2012

Mapping between quantum dot and quantum well lasers: From conventional to spin lasers

We explore similarities between the quantum wells and quantum dots used as optical gain media in semiconductor lasers. We formulate a mapping procedure which allows a simpler, often analytical, description of quantum well lasers to study more complex lasers based on quantum dots. The key observation in relating the two classes of laser is that the influence of a finite capture time on the operation of quantum dot lasers can be approximated well by a suitable choice of the gain compression factor in quantum well lasers. Our findings are applied to the rate equations for both conventional (spin-unpolarized) and spin lasers in which spin-polarized carriers are injected optically or electrically. We distinguish two types of mapping that pertain to the steady-state and dynamical operation respectively and elucidate their limitations.

cond-mat.mes-hall↗

arXiv2010

Theory of quantum dot spin-lasers

We formulate a model of a semiconductor Quantum Dot laser with injection of spin-polarized electrons. As compared to higher-dimensionality structures, the Quantum-Dot-based active region is known to improve laser properties, including the spin-related ones. The wetting layer, from which carriers are captured into the active region, acts as an intermediate level that strongly influences the lasing operation. The finite capture rate leads to an increase of lasing thresholds, and to saturation of emitted light at higher injection. In spite of these issues, the advantageous threshold reduction, resulting from spin injection, can be preserved. The "spin-filtering" effect, i.e., circularly polarized emission at even modest spin-polarization of injection, remains present as well. Our rate-equations description allows to obtain analytical results and provides transparent guidance for improvement of spin-lasers.

cond-mat.mes-hall↗