Electron localization induced by intrinsic anion disorder in a transition metal oxynitride

AbstractAnderson localization derived from randomness plays a crucial role in various kinds of phase transitions. Although treated as a free variable parameter in theory, randomness in electronic materials is hard to control experimentally owing to the coexisting Coulomb interaction. Here we demonstrate that the intrinsic anion disorder in a mixed-anion system of SrNbO2N induces a significant random potential that overwhelms the Coulomb potential while maintaining the lattice structure. A metal-to-insulator transition is triggered by a chemical modulation of the electron density where the critical electron density is more than three orders of magnitude greater than that predicted by the well-known Mott criterion. The localized electrons show characteristic electrical properties such as temperature-dependent multiple crossovers of conduction mechanisms and a positive magnetoresistance above 50% at low temperature. The large magnetoresistance is attributed to wave-function shrinkage of the localized states and clearly visualizes the anisotropy in the band structure, which indicates a compatibility of the periodicity and randomness.

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Quantitative Identification of Constituent Phases in a Nd-Fe-B Sintered Magnet and Temperature-Dependent Change in the Electron Density of Nd 2Fe 14B Studied by Synchrotron X-Ray Diffraction

SSRN Electronic Journal ◽

10.2139/ssrn.3414006 ◽

2019 ◽

Author(s):

Hiroyuki Okazaki ◽

David Billington ◽

Naruki Tsuji ◽

Wakana Ueno ◽

Yoshinori Kotani ◽

...

Keyword(s):

Electron Density ◽

X Ray Diffraction ◽

Temperature Dependent ◽

Sintered Magnet ◽

X Ray ◽

Dependent Change ◽

Quantitative Identification

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Temperature dependent conduction and UV induced metal-to-insulator transition in ZnO nanowires

Applied Physics Letters ◽

10.1063/1.2937847 ◽

2008 ◽

Vol 92 (21) ◽

pp. 212113 ◽

Cited By ~ 45

Author(s):

Pai-Chun Chang ◽

Jia Grace Lu

Keyword(s):

Zno Nanowires ◽

Insulator Transition ◽

Temperature Dependent ◽

Metal To Insulator Transition

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Bodies in the chloroplasts of sugar-beet infected by mosaic virus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100082807 ◽

1978 ◽

Vol 36 (2) ◽

pp. 388-389

Author(s):

Tulegenov Tursunbai A

Keyword(s):

Sugar Beet ◽

Mosaic Virus ◽

Electron Density ◽

Cross Sections ◽

Inclusion Bodies ◽

Lattice Structure ◽

Three Dimensional ◽

Epidermal Tissue ◽

Single Membrane ◽

Angle Section

Beet mosaic virus (Potyvirus group ) induced two types of inclusion bodies in the chloroplasts of the cells of epidermal tissue of sugar-beet. The crystalline type of inclussions having six-edged form is the largest one and it is of the higher electron density(Pig. 1. ). The size of their edges is depended on the angle section and it is changing from 0, 33μ to 1, 5μ. The quantity of them is constant. Comparasion of large number of sections gives us the oppotunity to suppose that these inclusions in three-dimensional measuring present itselves in a form of six-edged prism, oriented along the length of the chloroplasts. Exceptions may also take place. There are met crystalls with 4-5 edges.The largest inclusion bodies copy the form of the external membrane of chloroplasts and have rounded forms or protuberant edges. (Fig. 2. ). Crystals are devided from the stroma of chloroplast with the help of single membrane (M) placing near the edges. In large magnifications in longitudinal sections of the crystals a striation(with periodicity of 7, 4 nm) is revealed. In cross sections they have lattice structure.

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Optical Spectroscopy of Ingan Epilayers in the Low Indium Composition Regime

MRS Proceedings ◽

10.1557/proc-595-f99w11.41 ◽

1999 ◽

Vol 595 ◽

Cited By ~ 1

Author(s):

M. H. Crawford ◽

J. Han ◽

M. A. Banas ◽

S. M. Myers ◽

G. A. Petersen ◽

...

Keyword(s):

Room Temperature ◽

Radiative Decay ◽

Thermal Quenching ◽

Localized States ◽

Spectral Variation ◽

Temperature Dependent ◽

Time Resolved ◽

Decay Times ◽

Integrated Intensity ◽

Si Doped

AbstractPhotoluminescence (PL) spectroscopy was carried out on a series of Si-doped bulk InGaN films in the low indium (In) composition regime. Room temperature PL showed a factor of 25 increase in integrated intensity as the In composition was increased from 0 to 0.07. Temperature dependent PL data was fit to an Arrhenius equation to reveal an increasing activation energy for thermal quenching of the PL intensity as the In composition is increased. Time resolved PL measurements revealed that only the sample with highest In ( x=0.07) showed a strong spectral variation in decay time across the T=4K PL resonance, indicative of recombination from localized states at low temperatures. The decay times at room temperature were non-radiatively dominated for all films, and the room temperature (non-radiative) decay times increased with increasing In, from 50-230 psec for x=0-0.07. Our data demonstrate that non-radiative recombination is less effective with increasing In composition.

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Quantitative identification of constituent phases in a Nd-Fe-B-Cu sintered magnet and temperature dependent change of electron density of Nd2Fe14B studied by synchrotron X-ray diffraction

Acta Materialia ◽

10.1016/j.actamat.2019.10.004 ◽

2019 ◽

Vol 181 ◽

pp. 530-536 ◽

Cited By ~ 3

Author(s):

Hiroyuki Okazaki ◽

David Billington ◽

Naruki Tsuji ◽

Wakana Ueno ◽

Yoshinori Kotani ◽

...

Keyword(s):

Electron Density ◽

X Ray Diffraction ◽

Temperature Dependent ◽

Sintered Magnet ◽

X Ray ◽

Dependent Change ◽

Quantitative Identification

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Finite Deformation Elastoplasticity for Rate and Temperature Dependent Polycrystalline Metals

Volume 8: Mechanics of Solids, Structures and Fluids; Vibration, Acoustics and Wave Propagation ◽

10.1115/imece2011-63179 ◽

2011 ◽

Author(s):

Richard A. Regueiro ◽

Douglas J. Bammann ◽

Esteban B. Marin ◽

George C. Johnson

Keyword(s):

Internal State ◽

Lattice Structure ◽

Deformation Gradient ◽

State Variables ◽

Temperature Dependent ◽

Multiplicative Decomposition ◽

Strain Rate Effects ◽

Internal State Variables ◽

Polycrystalline Metals ◽

Rate Effects

An elastoplasticity model is formulated and demonstrated in one-dimension (1D) for modeling finite deformations in poly-crystalline metals. Quasi-static to high strain rate effects as well as temperature sensitivity are included. A multiplicative decomposition of the deformation gradient into elastic, plastic, and thermal parts, that includes a volumetric/isochoric split of the elastic stretching tensor is assumed. The kinematics and thermodynamic formulation lead to constitutive equations, stresses, and constraints on the evolution of the internal state variables. The model accounts for (i) dislocation drag effects on flow stress, and (ii) generation (hardening) and annihilation (recovery) of statistically-stored dislocations (SSDs). The resulting model is normalized to dimensionless form to allow dimensionless material parameters fit for one metal to approximate the behavior of another metal of similar lattice structure, if data are limited. One dimensional material parameter fitting is demonstrated for two refractory metals, body centered cubic (bcc) Tantalum and Tungsten.

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X-Ray Induced Insulator-Metal Transitions in CMR Manganites

MRS Proceedings ◽

10.1557/proc-494-65 ◽

1997 ◽

Vol 494 ◽

Cited By ~ 2

Author(s):

V. Kiryukhin ◽

D. Casa ◽

B. Keimer ◽

J. P. Hill ◽

A. Vigliante ◽

...

Keyword(s):

Lattice Structure ◽

Charge Ordering ◽

X Ray Diffraction ◽

Temperature Dependent ◽

X Ray ◽

Practical Applications ◽

Transitional State ◽

Current Voltage ◽

Highly Nonlinear ◽

Type Of Transition

ABSTRACTIn this work we report a study of the photoinduced insulator-to-metal transition in manganese oxide perovskites of the formula Pr1-xCaxMnO3. The transition is closely related to the magnetic field induced insulator-to-metal transition (CMR effect) observed in these materials. It is accompanied by a dramatic change in the magnetic properties and lattice structure: the material changes from an insulating charge-ordered canted antiferromagnet to a ferromagnetic metal. We present an investigation of the transport and structural properties of these materials over the course of the transition (which usually takes about an hour to complete). The current-voltage characteristics exhibited by the material during the transition are highly nonlinear, indicating a large inhomogeneity of the transitional state. Possible practical applications of this novel type of transition are briefly discussed. We also report a high-resolution x-ray diffraction study of the charge-ordering in these materials. The temperature dependent charge ordering structure observed in these compounds is more complex than previously reported.

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Optical Spectroscopy of Ingan Epilayers in the Low Indium Composition Regime

MRS Internet Journal of Nitride Semiconductor Research ◽

10.1557/s1092578300004981 ◽

2000 ◽

Vol 5 (S1) ◽

pp. 717-724

Author(s):

M. H. Crawford ◽

J. Han ◽

M. A. Banas ◽

S. M. Myers ◽

G. A. Petersen ◽

...

Keyword(s):

Room Temperature ◽

Radiative Decay ◽

Thermal Quenching ◽

Localized States ◽

Spectral Variation ◽

Temperature Dependent ◽

Time Resolved ◽

Decay Times ◽

Integrated Intensity ◽

Si Doped

Photoluminescence (PL) spectroscopy was carried out on a series of Si-doped bulk InGaN films in the low indium (In) composition regime. Room temperature PL showed a factor of 25 increase in integrated intensity as the In composition was increased from 0 to 0.07. Temperature dependent PL data was fit to an Arrhenius equation to reveal an increasing activation energy for thermal quenching of the PL intensity as the In composition is increased. Time resolved PL measurements revealed that only the sample with highest In (x=0.07) showed a strong spectral variation in decay time across the T=4K PL resonance, indicative of recombination from localized states at low temperatures. The decay times at room temperature were non-radiatively dominated for all films, and the room temperature (non-radiative) decay times increased with increasing In, from 50-230 psec for x=0-0.07. Our data demonstrate that non-radiative recombination is less effective with increasing In composition.

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Tunneling between parallel one-dimensional Wigner crystals

10.21203/rs.3.rs-986740/v1 ◽

2021 ◽

Author(s):

Reyna Mendez-Camacho ◽

Esteban Cruz-Hernandez

Keyword(s):

Electron Density ◽

Self Assembly ◽

Electron Tunneling ◽

Three Dimensional ◽

Localized States ◽

Electron Interaction ◽

Geometrical Parameters ◽

Wigner Crystals ◽

Quantum Electron ◽

Potential Applications

Abstract Vertically aligned arrays are a frequent outcome in the nanowires synthesis by self-assembly techniques or in its subsequent processing. When these nanowires are close enough, quantum electron tunneling is expected between them. Then, because extended or localized electronic states can be established in the wires by tuning its electron density, the tunneling configuration between adjacent wires could be conveniently adjusted by an external gate. In this contribution, by considering the collective nature of electrons using a Yukawa-like effective potential, we explore the electron interaction between closely spaced, parallel nanowires while varying the electron density and geometrical parameters. We find that, at a low-density Wigner crystal regime, the tunneling can take place between adjacent localized states along and transversal to the wires axis, which in turn allows to create two- and three-dimensional electronic distributions with valuable potential applications.

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