Structural, Optical, and Magnetic Properties of Co Doped CdTe Alloy Powders Prepared by Solid-State Reaction Method
TL;DR: In this paper, the effect of Co doping on structural, optical, and magnetic properties of CdTe powders has been studied using X-ray diffraction studies and solid state reaction method.
Abstract: Co doped CdTe powder samples were prepared by solid-state reaction method In the present work effect of Co doping on structural, optical, and magnetic properties has been studied X-ray diffraction studies confirm zinc blend structure for all the samples The lattice parameter showed linear increase with the increase in Co content The elemental constituents were characterized by EDAX Optical studies showed the increase in band gap with increase in Co level The samples were diluted magnetic semiconductors and exhibited clear hysteresis loop showing room temperature ferromagnetism as confirmed by vibrating sample magnetometer
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TL;DR: In this paper, structural, elastic, electronic properties of Cd 0.75 Ti 0.25 Z (Z = S, Se, Te) alloys were investigated to reveal the thermodynamic stability in the ferromagnetic state, further confirmed in terms of the enthalpy of formation ( ΔH ) and the cohesive energy.
Abstract: The present article encompasses detailed investigations of structural, elastic, electronic properties to understand magnetic, optical and thermoelectric behaviors of Cd 0.75 Ti 0.25 Z (Z = S, Se, Te) alloys. The optimized structures have been used to reveal the thermodynamic stability in the ferromagnetic state, which is further confirmed in terms of the enthalpy of formation ( ΔH ) and the cohesive energy. The ferromagnetic and semiconducting natures are explained through the band structures (BS) and the density of states (DOS). The analysis of the exchange constants ( N 0 α and N 0 β ) reveals that N 0 β induces large splitting of Ti 3 d -states due to its more negative values compared with N 0 α , hence, strong p-d hybridization induces ferromagnetism because the exchange field overcomes the crystal field. Moreover, the magnetic moment of Ti reduces by inducing traces of magnetic moments on the nonmagnetic sites due to strong p-d hybridization. The computed Curie temperatures ( T c ) indicate that alloys show above room temperature ferromagnetism (RTFM). The potential optoelectronic applications are elucidated by comparing e 1 (0) and E g , which are related through Penn's model. The blue shift of the absorption in the visible region caused by Ti doping make the studied materials potential candidate for magneto-optical and solar cell technology. Although Ti doping degrades overall thermoelectric performance, however, increased power factor at low temperatures in Ti doped CdS evidences that the studied compounds may find potential thermoelectric device applications.
50 citations
TL;DR: In this article, powder X-ray diffractometer (XRD), UV-Vis-NIR diffuse reflectance spectrophotometer, fluorescence spectrograph, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM).
Abstract: Tin doped ZnS powders (Zn 1−x Sn x S, x = 0.00, 0.02, 0.05&0.08) were synthesized by a simple Solid state reaction and were characterized by Powder X-ray diffractometer (XRD), UV–Vis–NIR diffuse reflectance spectrophotometer, fluorescence spectrophotometer, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The XRD studies revealed that no change in crystal structure was observed by the substitution of Sn into ZnS lattice. The crystallite size was calculated by Scherrer's formula and found that the crystallize size of Sn doped ZnS powders were in the range of 35–45 nm. From the diffused reflectance spectra, the band gap values of Zn 1−x Sn x S powders were estimated, and they were found to be in the range of 3.53–3.58 eV. The pure ZnS particles showed higher optical absorption in visible region than that of Sn doped ZnS nano particles. The Photoluminescence (PL) spectra of Zn 1−x Sn x S powders were recorded in the range of 400–700 nm with an excitation wavelength of 360 nm. The Zn 1−x Sn x S powders exhibited ferromagnetism at low temperature (100 K) and super paramagnetism at room temperature (300 K). The strength of magnetization increased with increase of Sn doping concentration from 0.015 emu/g to 0.18 emu/g, when x increased from 0.00–0.05.
33 citations
TL;DR: In this article, the effects of Co doping and thermal annealing on structural, optical, electrical and magnetic properties of CdS thin films were investigated and it was observed from photoluminescence spectra that all samples had two broad peaks around 380-500nm and 520-700nm.
Abstract: Chemical bath deposition method was used for preparation of Cd 1− x Co x S thin films. The effects of Co doping and thermal annealing on structural, optical, electrical and magnetic properties of CdS thin films were investigated. X-ray diffraction studies showed that the textures of all Cd 1− x Co x S thin films were cubic with (1 1 1) preferred direction. It was determined from Scanning electron microcopy micrographs that grain size of the samples was found to be around 150 nm. Optical transmittance of the CdS thin films decreased from ∼85% to ∼65% with Co doping. It was observed from photoluminescence spectra that all samples had two broad peaks around 380–500 nm and 520–700 nm. The resistivity value of Co doped samples was higher than that of undoped CdS. The undoped and Co doped CdS thin films showed a ferromagnetic behavior at room temperature.
17 citations
TL;DR: In this paper, X-ray diffraction (XRD) analysis by Maud software confirmed the desired crystallographic phase of both samples and also the substitution of Ni2+ ion in Dy2O3 lattice.
Abstract: Nanocrystalline samples of undoped dysprosium oxide (Dy2O3) and Ni2+ doped Dy2O3 (Dy1.90Ni0.10O3-δ/DNO) are prepared by co-precipitation method. X-ray diffraction (XRD) analysis by Maud software confirmed the desired crystallographic phase of both samples and also the substitution of Ni2+ ion in Dy2O3 lattice. Absence of impurity is confirmed from Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR) and high resolution transmission electron microscope (HRTEM) analysis. Magnetization vs. field (M-H) loop of DNO recorded at 5 and 10 K shows clear hysteresis loop with magnetization ∼138.71 emu/g at 5 K and ∼121.52 emu/g at 10 K with applied magnetic field of 5 T. The deviation of inverse susceptibility vs. temperature curve from Curie-Weiss fitting below ∼30 K and also the deviation of initial magnetization data of M-H loop recorded at 30 K from linear fitting suggests that the DNO is in mixed paramagnetic and ferromagnetic phase at and below ∼30 K. Defect mediated ferromagnetic ordering found in DNO at low temperature, is analyzed by bound magnetic polaron model.
14 citations
References
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TL;DR: The effective ionic radii of Shannon & Prewitt [Acta Cryst. (1969), B25, 925-945] are revised to include more unusual oxidation states and coordinations as mentioned in this paper.
Abstract: The effective ionic radii of Shannon & Prewitt [Acta Cryst. (1969), B25, 925-945] are revised to include more unusual oxidation states and coordinations. Revisions are based on new structural data, empirical bond strength-bond length relationships, and plots of (1) radii vs volume, (2) radii vs coordination number, and (3) radii vs oxidation state. Factors which affect radii additivity are polyhedral distortion, partial occupancy of cation sites, covalence, and metallic character. Mean Nb5+-O and Mo6+-O octahedral distances are linearly dependent on distortion. A decrease in cation occupancy increases mean Li+-O, Na+-O, and Ag+-O distances in a predictable manner. Covalence strongly shortens Fe2+-X, Co2+-X, Ni2+-X, Mn2+-X, Cu+-X, Ag+-X, and M-H- bonds as the electronegativity of X or M decreases. Smaller effects are seen for Zn2+-X, Cd2+-X, In2+-X, pb2+-X, and TI+-X. Bonds with delocalized electrons and therefore metallic character, e.g. Sm-S, V-S, and Re-O, are significantly shorter than similar bonds with localized electrons.
51,997 citations
TL;DR: This review describes a new paradigm of electronics based on the spin degree of freedom of the electron, which has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices.
Abstract: This review describes a new paradigm of electronics based on the spin degree of freedom of the electron. Either adding the spin degree of freedom to conventional charge-based electronic devices or using the spin alone has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices. To successfully incorporate spins into existing semiconductor technology, one has to resolve technical issues such as efficient injection, transport, control and manipulation, and detection of spin polarization as well as spin-polarized currents. Recent advances in new materials engineering hold the promise of realizing spintronic devices in the near future. We review the current state of the spin-based devices, efforts in new materials fabrication, issues in spin transport, and optical spin manipulation.
9,917 citations
"Structural, Optical, and Magnetic P..." refers background in this paper
...The unique properties of DMS attracted the scientific community and are extensively studied for their distinctive behavior in spintronic devices which allow control of both the spin and the charge of carriers [3, 4]....
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TL;DR: The magnetic coupling in all semiconductor ferromagnetic/nonmagnetic layered structures, together with the possibility of spin filtering in RTDs, shows the potential of the present material system for exploring new physics and for developing new functionality toward future electronics.
Abstract: REVIEW Semiconductor devices generally take advantage of the charge of electrons, whereas magnetic materials are used for recording information involving electron spin. To make use of both charge and spin of electrons in semiconductors, a high concentration of magnetic elements can be introduced in nonmagnetic III-V semiconductors currently in use for devices. Low solubility of magnetic elements was overcome by low-temperature nonequilibrium molecular beam epitaxial growth, and ferromagnetic (Ga,Mn)As was realized. Magnetotransport measurements revealed that the magnetic transition temperature can be as high as 110 kelvin. The origin of the ferromagnetic interaction is discussed. Multilayer heterostructures including resonant tunneling diodes (RTDs) have also successfully been fabricated. The magnetic coupling between two ferromagnetic (Ga,Mn)As films separated by a nonmagnetic layer indicated the critical role of the holes in the magnetic coupling. The magnetic coupling in all semiconductor ferromagnetic/nonmagnetic layered structures, together with the possibility of spin filtering in RTDs, shows the potential of the present material system for exploring new physics and for developing new functionality toward future electronics.
4,339 citations
"Structural, Optical, and Magnetic P..." refers background in this paper
...The unique properties of DMS attracted the scientific community and are extensively studied for their distinctive behavior in spintronic devices which allow control of both the spin and the charge of carriers [3, 4]....
[...]
TL;DR: In this paper, the physical properties of diluted magnetic semiconductors (DMS) of the type AII1−xMnxBVI (e.g., Cd1−mnxSe, Hg 1−mnsTe) were reviewed.
Abstract: We review the physical properties of diluted magnetic semiconductors (DMS) of the type AII1−xMnxBVI (e.g., Cd1−xMnxSe, Hg1−xMnxTe). Crystallographic properties are discussed first, with emphasis on the common structural features which these materials have as a result of tetrahedral bonding. We then describe the band structure of the AII1−xMnxBVI alloys in the absence of an external magnetic field, stressing the close relationship of the sp electron bands in these materials to the band structure of the nonmagnetic AIIBVI ‘‘parent’’ semiconductors. In addition, the characteristics of the narrow (nearly localized) band arising from the half‐filled Mn 3d5 shells are described, along with their profound effect on the optical properties of DMS. We then describe our present understanding of the magnetic properties of the AII1−xMnxBVI alloys. In particular, we discuss the mechanism of the Mn++‐Mn++ exchange, which underlies the magnetism of these materials; we present an analytic formulation for the magnetic susc...
2,895 citations
"Structural, Optical, and Magnetic P..." refers background in this paper
...Though room temperature ferromagnetism was reported in II-VI DMS in both experimentally and theoretically investigations by several researchers, the exact origin of magnetism in DMS is still a challenge to scientific community....
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...II-VI DMS systems are particularly interesting, since doping of magnetic ions in II-VI systems is more effective than metal oxide systems....
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...II-VI based DMS with Mn as the dopant has been studied extensively, but the studies with other magnetic dopants like Fe, Co, Ni, and so forth are meager....
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...In recent years, considerable amount of research work has been devoted to form new DMS and to improve the ferromagnetic properties of the known DMS in an effort to develop new spintronic devices, such as spin valves, spin light emitting diodes, magnetic sensors, logic devices, and ultrafast optical switches [2]....
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...In order to realize the practical implication of spin-based devices, DMS must exhibit room temperature ferromagnetism....
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TL;DR: In this article, the authors summarize recent progress in dilute magnetic semiconductors (DMS) such as (Ga, Mn)N, (Ga and Mn)P, (Zn, Mn), O, and SiGeN2 exhibiting room temperature ferromagnetic properties.
Abstract: Existing semiconductor electronic and photonic devices utilize the charge on electrons and holes in order to perform their specific functionality such as signal processing or light emission. The relatively new field of semiconductor spintronics seeks, in addition, to exploit the spin of charge carriers in new generations of transistors, lasers and integrated magnetic sensors. The ability to control of spin injection, transport and detection leads to the potential for new classes of ultra-low power, high speed memory, logic and photonic devices. The utility of such devices depends on the availability of materials with practical (>300 K) magnetic ordering temperatures. In this paper, we summarize recent progress in dilute magnetic semiconductors (DMS) such as (Ga, Mn)N, (Ga, Mn)P, (Zn, Mn)O and (Zn, Mn)SiGeN2 exhibiting room temperature ferromagnetism, the origins of the magnetism and its potential applications in novel devices such as spin-polarized light emitters and spin field effect transistors.
438 citations
"Structural, Optical, and Magnetic P..." refers background in this paper
...In recent years, considerable amount of research work has been devoted to form new DMS and to improve the ferromagnetic properties of the known DMS in an effort to develop new spintronic devices, such as spin valves, spin light emitting diodes, magnetic sensors, logic devices, and ultrafast optical switches [2]....
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