The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
K Ando - One of the best experts on this subject based on the ideXlab platform.
-
room temperature ferromagnetism in a ii vi diluted Magnetic Semiconductor zn 1 x cr x te
Physical Review Letters, 2003Co-Authors: H Saito, V Zayets, S Yamagata, K AndoAbstract:The Magnetic and magneto-optical properties of a Cr-doped II-VI Semiconductor ZnTe were investigated. Magnetic circular dichroism measurements showed a strong interaction between the $sp$ carriers and localized $d$ spins, indicating that ${\mathrm{Z}\mathrm{n}}_{1\ensuremath{-}x}{\mathrm{C}\mathrm{r}}_{x}\mathrm{T}\mathrm{e}$ is a diluted Magnetic Semiconductor. The Curie temperature of the film with $x=0.20$ was estimated to be $300\ifmmode\pm\else\textpm\fi{}10\text{ }\mathrm{K}$, which is the highest value ever reported for a diluted Magnetic Semiconductor in which $sp\mathrm{\text{\ensuremath{-}}}d$ interactions were confirmed. In spite of its high Curie temperature, ${\mathrm{Z}\mathrm{n}}_{1\ensuremath{-}x}{\mathrm{C}\mathrm{r}}_{x}\mathrm{T}\mathrm{e}$ film shows semiconducting electrical transport properties.
-
room temperature ferromagnetism in a ii vi diluted Magnetic Semiconductor zn 1 x cr x te
Physical Review Letters, 2003Co-Authors: H Saito, V Zayets, S Yamagata, K AndoAbstract:The Magnetic and magneto-optical properties of a Cr-doped II-VI Semiconductor ZnTe were investigated. Magnetic circular dichroism measurements showed a strong interaction between the sp carriers and localized d spins, indicating that Zn(1-x)Cr(x)Te is a diluted Magnetic Semiconductor. The Curie temperature of the film with x=0.20 was estimated to be 300+/-10 K, which is the highest value ever reported for a diluted Magnetic Semiconductor in which sp-d interactions were confirmed. In spite of its high Curie temperature, Zn(1-x)Cr(x)Te film shows semiconducting electrical transport properties.
-
magneto optic effect of the ferroMagnetic diluted Magnetic Semiconductor ga1 xmnxas
Journal of Applied Physics, 1998Co-Authors: K Ando, T Hayashi, M Tanaka, A TwardowskiAbstract:Magnetic circular dichroism (MCD) of a ferroMagnetic diluted Magnetic Semiconductor Ga1−xMnxAs films was measured to clarify their electronic structure. Strong enhancement of MCD by Mn substitution indicated a strong sp–d hybridization. The p–d exchange interaction was concluded to be antiferroMagnetic, which was in contrast with the reported ferroMagnetic p–d exchange in very diluted paraMagnetic GaAs:Mn bulk crystals. The change of the character of the p–d exchange interaction is due to the unique feature of Ga1−xMnxAs that the relative abundance of the neutral and ionized Mn acceptors controls the p–d exchange.
Daniel R Gamelin - One of the best experts on this subject based on the ideXlab platform.
-
above room temperature ferroMagnetic ni2 doped zno thin films prepared from colloidal diluted Magnetic Semiconductor quantum dots
Applied Physics Letters, 2004Co-Authors: Dana A Schwartz, Kevin R Kittilstved, Daniel R GamelinAbstract:We report the preparation of spin-coated nickel-doped zinc oxide nanocrystalline thin films using high-quality colloidal diluted Magnetic Semiconductor (DMS) quantum dots as solution precursors. These films show robust ferromagnetism with Curie temperatures above 350K and 300K saturation moments up to 0.1Bohr magnetons per nickel. These results demonstrate a step toward the use of colloidal zero-dimensional DMS nanocrystals as building blocks for the bottom-up construction of more complex ferroMagnetic Semiconductor nanostructures.
-
high temperature ferromagnetism in ni2 doped zno aggregates prepared from colloidal diluted Magnetic Semiconductor quantum dots
Physical Review Letters, 2003Co-Authors: Pavle V Radovanovic, Daniel R GamelinAbstract:Ferromagnetism with T c > 350 K is observed in the diluted Magnetic Semiconductor Ni 2 + :ZnO synthesized from solution. Whereas colloidal Ni 2 + :ZnO nanocrystals are paraMagnetic, their aggregation gives rise to robust ferromagnetism. The appearance of ferromagnetism is attributed to the increase in domain volumes and the generation of lattice defects upon aggregation. The unusual temperature dependence of the magnetization coercivity is discussed in terms of a temperature-dependent exchange interaction involving paraMagnetic Ni 2 + ions.
-
electronic absorption spectroscopy of cobalt ions in diluted Magnetic Semiconductor quantum dots demonstration of an isocrystalline core shell synthetic method
Journal of the American Chemical Society, 2001Co-Authors: Pavle V Radovanovic, Daniel R GamelinAbstract:This paper reports the application of ligand-field electronic absorption spectroscopy to probe Co(2+) dopant ions in diluted Magnetic Semiconductor quantum dots. It is found that standard inverted micelle coprecipitation methods for preparing Co(2+)-doped CdS (Co(2+):CdS) quantum dots yield dopant ions predominantly bound to the nanocrystal surfaces. These Co(2+):CdS nanocrystals are unstable with respect to solvation of surface-bound Co(2+), and time-dependent absorption measurements allow identification of two transient surface-bound intermediates involving solvent-cobalt coordination. Comparison with Co(2+):ZnS quantum dots prepared by the same methods, which show nearly isotropic dopant distribution, indicates that the large mismatch between the ionic radii of Co(2+) (0.74 A) and Cd(2+) (0.97 A) is responsible for exclusion of Co(2+) ions during CdS nanocrystal growth. An isocrystalline core/shell preparative method is developed that allows synthesis of internally doped Co(2+):CdS quantum dots through encapsulation of surface-bound ions beneath additional layers of CdS.
Masashi Kawasaki - One of the best experts on this subject based on the ideXlab platform.
-
rutile type oxide diluted Magnetic Semiconductor mn doped sno2
Applied Physics Letters, 2002Co-Authors: Hisamichi Kimura, Tsuyoshi Hasegawa, Tomoteru Fukumura, Masashi Kawasaki, K Inaba, Hideomi KoinumaAbstract:Epitaxial films of an oxide-diluted Magnetic Semiconductor with rutile structure, Mn-doped SnO2, have been fabricated by pulsed-laser deposition. As the Mn content increases, systematic changes in lattice constants and in-gap absorption are observed. Magnetization measurements show almost paraMagnetic behavior. The injection of n-type carrier over 1020 cm−3 is achieved by Sb doping. A Sn0.95Mn0.05O2:Sb film shows giant positive magnetoresistance as large as 60% at 5 K.
-
Magnetic properties of mn doped zno
Applied Physics Letters, 2001Co-Authors: Tomoteru Fukumura, Zhengwu Jin, Tsuneo Shono, Shin-ya Koshihara, Tsuyoshi Hasegawa, Masashi Kawasaki, Hideomi KoinumaAbstract:We report on the Magnetic properties of an oxide-diluted Magnetic Semiconductor (DMS), Zn0.64Mn0.36O. The temperature dependence of the magnetization shows a spin-glass behavior with the large magnitude of the Curie–Weiss temperature, corresponding to a stronger antiferroMagnetic exchange coupling than other II–VI DMSs. The small effective Mn moment (x∼0.02) under high field also represents a strong antiferroMagnetic exchange coupling in this compound.We report on the Magnetic properties of an oxide-diluted Magnetic Semiconductor (DMS), Zn0.64Mn0.36O. The temperature dependence of the magnetization shows a spin-glass behavior with the large magnitude of the Curie–Weiss temperature, corresponding to a stronger antiferroMagnetic exchange coupling than other II–VI DMSs. The small effective Mn moment (x∼0.02) under high field also represents a strong antiferroMagnetic exchange coupling in this compound.
-
an oxide diluted Magnetic Semiconductor mn doped zno
Applied Physics Letters, 1999Co-Authors: Tomoteru Fukumura, Zhengwu Jin, Hideomi Koinuma, Akira Ohtomo, Masashi KawasakiAbstract:Epitaxial thin films of an oxide-diluted Magnetic Semiconductor, Mn-doped ZnO, were fabricated by pulsed-laser deposition technique. Solubility of Mn into ZnO exceeds thermal equilibrium limit as a result of nonequilibrium film growth process. As Mn content is increased, the lattice constants of both a and c axes of wurtzite Zn1−xMnxO films (x<0.35) increase and the band gap expands although considerable in-gap absorption develops. Itinerant electrons over 1019 cm−3 can be doped into the Zn1−xMnxO films by Al doping, in contrast to low carrier density in the other II–VI diluted Magnetic Semiconductors. The temperature dependence of the resistivity is almost metallic and considerable magnetoresistance is observed at low temperatures.
Hideomi Koinuma - One of the best experts on this subject based on the ideXlab platform.
-
rutile type oxide diluted Magnetic Semiconductor mn doped sno2
Applied Physics Letters, 2002Co-Authors: Hisamichi Kimura, Tsuyoshi Hasegawa, Tomoteru Fukumura, Masashi Kawasaki, K Inaba, Hideomi KoinumaAbstract:Epitaxial films of an oxide-diluted Magnetic Semiconductor with rutile structure, Mn-doped SnO2, have been fabricated by pulsed-laser deposition. As the Mn content increases, systematic changes in lattice constants and in-gap absorption are observed. Magnetization measurements show almost paraMagnetic behavior. The injection of n-type carrier over 1020 cm−3 is achieved by Sb doping. A Sn0.95Mn0.05O2:Sb film shows giant positive magnetoresistance as large as 60% at 5 K.
-
Magnetic properties of mn doped zno
Applied Physics Letters, 2001Co-Authors: Tomoteru Fukumura, Zhengwu Jin, Tsuneo Shono, Shin-ya Koshihara, Tsuyoshi Hasegawa, Masashi Kawasaki, Hideomi KoinumaAbstract:We report on the Magnetic properties of an oxide-diluted Magnetic Semiconductor (DMS), Zn0.64Mn0.36O. The temperature dependence of the magnetization shows a spin-glass behavior with the large magnitude of the Curie–Weiss temperature, corresponding to a stronger antiferroMagnetic exchange coupling than other II–VI DMSs. The small effective Mn moment (x∼0.02) under high field also represents a strong antiferroMagnetic exchange coupling in this compound.We report on the Magnetic properties of an oxide-diluted Magnetic Semiconductor (DMS), Zn0.64Mn0.36O. The temperature dependence of the magnetization shows a spin-glass behavior with the large magnitude of the Curie–Weiss temperature, corresponding to a stronger antiferroMagnetic exchange coupling than other II–VI DMSs. The small effective Mn moment (x∼0.02) under high field also represents a strong antiferroMagnetic exchange coupling in this compound.
-
an oxide diluted Magnetic Semiconductor mn doped zno
Applied Physics Letters, 1999Co-Authors: Tomoteru Fukumura, Zhengwu Jin, Hideomi Koinuma, Akira Ohtomo, Masashi KawasakiAbstract:Epitaxial thin films of an oxide-diluted Magnetic Semiconductor, Mn-doped ZnO, were fabricated by pulsed-laser deposition technique. Solubility of Mn into ZnO exceeds thermal equilibrium limit as a result of nonequilibrium film growth process. As Mn content is increased, the lattice constants of both a and c axes of wurtzite Zn1−xMnxO films (x<0.35) increase and the band gap expands although considerable in-gap absorption develops. Itinerant electrons over 1019 cm−3 can be doped into the Zn1−xMnxO films by Al doping, in contrast to low carrier density in the other II–VI diluted Magnetic Semiconductors. The temperature dependence of the resistivity is almost metallic and considerable magnetoresistance is observed at low temperatures.
Tomoteru Fukumura - One of the best experts on this subject based on the ideXlab platform.
-
rutile type oxide diluted Magnetic Semiconductor mn doped sno2
Applied Physics Letters, 2002Co-Authors: Hisamichi Kimura, Tsuyoshi Hasegawa, Tomoteru Fukumura, Masashi Kawasaki, K Inaba, Hideomi KoinumaAbstract:Epitaxial films of an oxide-diluted Magnetic Semiconductor with rutile structure, Mn-doped SnO2, have been fabricated by pulsed-laser deposition. As the Mn content increases, systematic changes in lattice constants and in-gap absorption are observed. Magnetization measurements show almost paraMagnetic behavior. The injection of n-type carrier over 1020 cm−3 is achieved by Sb doping. A Sn0.95Mn0.05O2:Sb film shows giant positive magnetoresistance as large as 60% at 5 K.
-
Magnetic properties of mn doped zno
Applied Physics Letters, 2001Co-Authors: Tomoteru Fukumura, Zhengwu Jin, Tsuneo Shono, Shin-ya Koshihara, Tsuyoshi Hasegawa, Masashi Kawasaki, Hideomi KoinumaAbstract:We report on the Magnetic properties of an oxide-diluted Magnetic Semiconductor (DMS), Zn0.64Mn0.36O. The temperature dependence of the magnetization shows a spin-glass behavior with the large magnitude of the Curie–Weiss temperature, corresponding to a stronger antiferroMagnetic exchange coupling than other II–VI DMSs. The small effective Mn moment (x∼0.02) under high field also represents a strong antiferroMagnetic exchange coupling in this compound.We report on the Magnetic properties of an oxide-diluted Magnetic Semiconductor (DMS), Zn0.64Mn0.36O. The temperature dependence of the magnetization shows a spin-glass behavior with the large magnitude of the Curie–Weiss temperature, corresponding to a stronger antiferroMagnetic exchange coupling than other II–VI DMSs. The small effective Mn moment (x∼0.02) under high field also represents a strong antiferroMagnetic exchange coupling in this compound.
-
an oxide diluted Magnetic Semiconductor mn doped zno
Applied Physics Letters, 1999Co-Authors: Tomoteru Fukumura, Zhengwu Jin, Hideomi Koinuma, Akira Ohtomo, Masashi KawasakiAbstract:Epitaxial thin films of an oxide-diluted Magnetic Semiconductor, Mn-doped ZnO, were fabricated by pulsed-laser deposition technique. Solubility of Mn into ZnO exceeds thermal equilibrium limit as a result of nonequilibrium film growth process. As Mn content is increased, the lattice constants of both a and c axes of wurtzite Zn1−xMnxO films (x<0.35) increase and the band gap expands although considerable in-gap absorption develops. Itinerant electrons over 1019 cm−3 can be doped into the Zn1−xMnxO films by Al doping, in contrast to low carrier density in the other II–VI diluted Magnetic Semiconductors. The temperature dependence of the resistivity is almost metallic and considerable magnetoresistance is observed at low temperatures.