Structure-Dependent Spin Polarization in Polymorphic CdS:Y Semiconductor Nanocrystals

Abstract

Searching for the polymorphic semiconductor nanocrystals would provide precise and insightful structure-spin polarization correlations and meaningful guidance for designing and synthesizing high spin-polarized spintronic materials. Herein, the high spin polarization is achieved in polymorphic CdS:Y semiconductor nanocrystals. The high-pressure polymorph of rock-salt CdS:Y nanocrystals has been recovered at ambient conditions synthesized by the wurtzite CdS:Y nanocrystals as starting material under 5.2 GPa and 300 °C conditions. The rock-salt CdS:Y polymorph displays more robust room-temperature ferromagnetism than wurtzite sample, which can reach the ferromagnetic level of conventional semiconductors doped with magnetic transition-metal ions, mainly due to the significantly enhanced spin configuration and defect states. Therefore, crystal structure directly governs the spin configuration, which determines the degree of spin polarization. This work can provide experimental and theoretical methods for designing the high spin-polarized semiconductor nanocrystals, which is important for applications in semiconductor spintronics.

High pressure: a feasible tool for the synthesis of unprecedented inorganic compounds

“…115 The dopant Y atom can not only greatly reduce the defect formation energy to generate more Cd vacancies, but also improve the magnetic properties of CdS with a wurtzite structure, and tend to form Cd vacancy defects in CdS with a rock-salt structure. 6 Nitride semiconductors are attractive because they can be environmentally benign and possess favourable electronic properties. CaZn 2 N 2 is a new compound predicted by DFT and synthesized under high pressure.…”

First-Principles Study of the Effect of Native Defects on Spin Polarization and Exchange Coupling Interaction in Semimetal V3O4

“…Macroscopic ferromagnetism is determined by spin polarization, which further depends on the difference between the spin-up and spin-down DOS at the Fermi level. 11,12 Curie temperature is determined by spin exchange coupling, which further depends on the difference in the total energies (ΔE) between antiferromagnetic (AFM) and ferromagnetic (FM) states. 13−18 In addition, the native defects could mediate carriers and introduce defect energy levels near the Fermi level, which provides an effective method to alter the spin polarization and spin exchange coupling interaction.…”

“…Macroscopic ferromagnetism is determined by spin polarization, which further depends on the difference between the spin-up and spin-down DOS at the Fermi level. , Curie temperature is determined by spin exchange coupling, which further depends on the difference in the total energies (Δ E ) between antiferromagnetic (AFM) and ferromagnetic (FM) states. − In addition, the native defects could mediate carriers and introduce defect energy levels near the Fermi level, which provides an effective method to alter the spin polarization and spin exchange coupling interaction. − Furthermore, it has been a long-standing goal to mediate intrinsic ferromagnetism without clustering of the magnetic elements and magnetic second phases introduced by a magnetic transition-metal dopant, which has led to the idea of d 0 ferromagnetism. , Therefore, a complete understanding of the physics of the role of native defects in spin polarization and exchange coupling interaction of the V 3 O 4 semimetal material provides an essential and effective method to mediate this d 0 ferromagnetism and Curie temperature, which is a key element in the application of the V 3 O 4 semimetal material in spintronics.…”

Doping-Concentration-Induced Ferromagnetism and Antiferromagnetism in In2S3:Dy3+ Quantum Dots

“…[14][15][16] Nowadays, much effort has been devoted to the exploration of these new DMS nanomaterials to achieve their practical applications, which at the same time provide precise and insightful guidance for designing and synthesizing unique spintronic materials. [17][18][19] Sulfide compounds with spinel-related structure become much more promising as a fascinating host material owing to their massive empty sites, which is particularly in favor of incorporation of guest ions. 20,21 Among various chalcogenide semiconductors, β-In 2 S 3 is a typical III-VI group defect spinel structured chalcogenide with a large amount of vacancies.…”

“…Nanoscale magnetism plays an increasingly significant role in new generation magnetic storage devices and microelectronic industries. − Especially some novel materials with Curie temperatures ( T c ) well in excess of room temperature and high saturation magnetization (Ms) remain a continuous priority. − Diluted magnetic semiconductor (DMS) quantum dots (QDs) , meet the aforementioned needs and have attracted considerable attention owing to their remarkable magneto-optical effect and three-dimensional quantum confinement of electrons and holes in recent years. − It opens the prospect of combining information processing and storage functionalities in one material and has potential applications in the emerging field of spin-based electronics or spintronics, , such as miniaturization of electronic devices, high density data storage systems, and magnetic fluids. − Nowadays, much effort has been devoted to the exploration of these new DMS nanomaterials to achieve their practical applications, which at the same time provide precise and insightful guidance for designing and synthesizing unique spintronic materials. − …”