Recent Advances in Magnetic Ion-Doped Semiconductor Quantum Dots

Abstract

Dilute magnetic semiconductor (DMS) quantum dots (QDs) have potential to be used as basic working components of spin-based electronic devices. Therefore it is important to study these materials from fundamental and technological viewpoints. Quantum confinement effects are known to enhance exchange interactions and induce properties that were previously not observed in bulk materials. In fact, properties are known to alter dramatically when dimensions are reduced to nanometre size regime. In this review we briefly discuss the recent advances in chemical (synthetic) and physical (properties) aspects of DMS QDs. We first discuss the various issues involved in the synthesis of DMS QDs followed by a discussion of the solutions obtained so far. We then discuss the interesting properties of DMS QDs with emphasis on their magnetic, magneto-optical and magneto-electrical properties arising from the cooperative effects of spinexchange interactions.

Dilute Magnetic Semiconducting Quantum Dots: Smart Materials for Spintronics

“…It has been observed that the effectiveness of interaction of sp-d for the exchange of carrier and magnetic ions in terms of hole energy depends on the high and low magnetic field induces from outside. Hence, it is expected that due to the small size of a quantum dot, the exchange and interaction of d electrons with sp shelled electrons will be extensive in DMSQDs [56]. Therefore, the spintronics devices developed from DMSQDs are expected to be efficient as well as miniaturized one, probably due to the quantum confinement effect of DMS and therefore better than the single DMS materials.…”

“…Unwanted oxidation can also be prevented during the adopted during the synthesis process. Fe, Co, Ni and Mn are the main doping elements used for the preparation of DMSQDs of semiconductors of Group II-VI [56].…”

“…They have achieved a magnetic moment of 80 memu/g at RT for doped CdS and undoped CdS showed negligible amount of magnetic moment with the same scale reaction. It has been observed that in the presence of an external magnetic field, a non-magnetic substance showed a small internal magnetic field due to Zeeman splitting (having an order of 2), whereas, materials like DMSQDs, the intensity of internal field is very high in the presence of external magnetic field [56]. It is also observed that along with the large internal field, a small external magnetic field also gets generated during this process.…”

Frontier challenges in doping quantum dots: synthesis and characterization

“…excitonic excited states introduced by strong dopant-carrier exchange coupling, red-shied PL emission bands arising from either the dopant d-d levels or the interaction of the dopant d level with the host, and several other applications. [20][21][22][23][24] The unpaired spins of these open shell transition metal dopants are magnetically or optically coupled to the free and photogenerated charge carriers, wherein the dopant-carrier spatial overlap determines the coupling strength. These sp-d exchange interactions are characteristic features resulting in magnetooptical and/or magneto-transport properties.…”

Quantum Dots and Fluorescent and Magnetic Nanocomposites: Recent Investigations and Applications in Biology and Medicine

“…The application of QDs for combined targeting and delivery of diagnostic and therapeutic agents can be further developed by a combination with magnetic separation techniques via the recent evolution of MQDs. In this chapter, among many benefits of MQDsbased separation to current procedures, one should also mention the small dimension of MQDs, which are small enough to possibly interact with single-cell biomarkers/cell surface receptors which results in corresponding quantification of the results [22,25]. These multifunctional fluorescent and magnetic nanoparticles of small dimension, which are MQDs, can target any biomolecule and can be separately controlled by engineering magnetic fields.…”