scholarly journals Critical enhancement of thermopower in a chemically tuned polar semimetal MoTe2

2016 ◽  
Vol 2 (11) ◽  
pp. e1601378 ◽  
Author(s):  
Hideaki Sakai ◽  
Koji Ikeura ◽  
Mohammad Saeed Bahramy ◽  
Naoki Ogawa ◽  
Daisuke Hashizume ◽  
...  
Keyword(s):  
Physical Properties ◽  
Transport Phenomena ◽  
Structural Instability ◽  
Electric Polarization ◽  
Thermoelectric Efficiency ◽  
Polar Order ◽  
Scattering Rate ◽  
Polar Transition ◽  
Quantum Paraelectrics ◽  
Energy Dependent

Ferroelectrics with spontaneous electric polarization play an essential role in today’s device engineering, such as capacitors and memories. Their physical properties are further enriched by suppressing the long-range polar order, as exemplified by quantum paraelectrics with giant piezoelectric and dielectric responses at low temperatures. Likewise in metals, a polar lattice distortion has been theoretically predicted to give rise to various unusual physical properties. However, to date, a “ferroelectric”-like transition in metals has seldom been controlled, and hence, its possible impacts on transport phenomena remain unexplored. We report the discovery of anomalous enhancement of thermopower near the critical region between the polar and nonpolar metallic phases in 1T′-Mo1−xNbxTe2with a chemically tunable polar transition. It is unveiled from the first-principles calculations and magnetotransport measurements that charge transport with a strongly energy-dependent scattering rate critically evolves toward the boundary to the nonpolar phase, resulting in large cryogenic thermopower. Such a significant influence of the structural instability on transport phenomena might arise from the fluctuating or heterogeneous polar metallic states, which would pave a novel route to improving thermoelectric efficiency.

Entangled exchange-spring magnetic structure driven by surface magnetic symmetry-breaking in Cr2O3 nanoparticles

2022 ◽  
Author(s):  
Natalia Rinaldi-Montes ◽  
Pedro Gorria ◽  
Antonio Benito Fuertes ◽  
David Martínez-Blanco ◽  
Zakariae Amghouz ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Physical Properties ◽  
Magnetic Structure ◽  
Room Temperature ◽  
Spontaneous Magnetization ◽  
Electric Polarization ◽  
Exchange Spring ◽  
Cr2o3 Nanoparticles ◽  
Magnetic Symmetry ◽  
Electric Effect

Bulk Cr2O3 is an antiferromagnetic oxide that exhibits the magneto-electric effect at room temperature, with neither spontaneous magnetization nor net electric polarization. These physical properties stem from a subtle competition...

Review of polyhedral distortions as a multi-scale minimization of the electric polarization and their correlations with physical properties

2006 ◽  
Vol 62 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Abderrahim Benabbas
Keyword(s):  
Physical Properties ◽  
Electron Density ◽  
Valence Electron ◽  
Cuprate Superconductors ◽  
Electric Polarization ◽  
Chemical Compositions ◽  
Multi Scale ◽  
Valence Electron Density ◽  
Formal Charge ◽  
Jahn Teller

The Jahn–Teller (JT) and non-Jahn–Teller polyhedral distortions are reviewed within the same context, based on a multi-scale minimization of the electric polarization by handling formal ionic valences and valence electron density. This model is applied to tetragonal distortions of octahedra, particularly in K2NiF4 structures with different formula types, along with doping. The predictions are always in good agreement with the observed data. In particular, the ferrodistortive order of JT distortions is obtained from formal charge polarizations, while the antiferrodistortive one is adopted when only the valence electron density is involved. The correlations between physical properties and octahedral elongations through the crystal structures on one side and chemical compositions on the other side are discussed according to this model for high-Tc cuprate superconductors and CMR manganites.

Effect of green manuring on the physical properties of soil under a rice–wheat cropping system

1994 ◽  
Vol 122 (1) ◽  
pp. 107-113 ◽  
Author(s):  
R. C. Joshi ◽  
D. D. Haokip ◽  
K. N. Singh
Keyword(s):  
Physical Properties ◽  
Unsaturated Soils ◽  
Cropping System ◽  
Structural Instability ◽  
Soil Physical Properties ◽  
Wheat Crop ◽  
New Delhi ◽  
Green Manures ◽  
Green Manuring ◽  
Npk Fertilizer

SUMMARYThe effects of green manuring with Sesbania aculeata, or with Leucaena leucocephala leaves and of weed incorporation on the physical properties of a clay loam soil under a rice–wheat rotation were compared at New Delhi, India, in 1986–87. Under puddled conditions, the volumetric moisture content of the saturated topsoils varied from 0·400 cm3/cm3 in the Sesbania-treated plots to 0·425 cm3/cm3 in plots receiving no green manure, but in the unsaturated soils at rice harvest the corresponding values were 0·317 and 0·271 cm3/cm3. The effects of the green manures on the water content of the soils were still evident after a subsequent wheat crop. Other soil physical properties affected by the treatments were the following (data refer to topsoils measured after the rice harvest): settling index (cm/cm), an estimate of structural instability, which ranged from 25·5% (Sesbania-treated plots), to 28·6% (weed incorporation), 29·7% (Leucaena-treated plots) and to 33·5% (NPK-fertilizer only). Soil dispersion increased from 6·0 to 10·0 g/100g through the same treatment sequence. Hydraulic conductivity in the NPK-fertilizer only plots was 31 cm/day, but increased to 4·8 cm/day in the Sesbania-trealed plots. Sesbania was superior to the other green manures for improving soil physical properties after its incorporation.

First principle studies on the structures, electronic properties and Raman spectrums of monolayer WX2 (X = S, Se, Te) under strain condition

2021 ◽  
pp. 2150135
Author(s):  
Shan Huang ◽  
Yanping Wang ◽  
Yawen Fan ◽  
Jinjiao Feng ◽  
Hui Zhao ◽  
...  
Keyword(s):  
Physical Properties ◽  
Electronic Properties ◽  
Density Functional ◽  
Tensile Strain ◽  
Phonon Dispersion ◽  
Compressive Strain ◽  
Transition Metal Dichalcogenides ◽  
Structural Instability ◽  
Metal Dichalcogenides ◽  
Different Strains

The two-dimensional transition-metal dichalcogenides (2D TMDs) WX2 (S, Se, Te) have received extensive attention and research since they have excellent physical properties and have been widely used in the fields of photoelectronics. Monolayer (ML) WX2 has excellent physical properties and can be modified by simple strain. Using the first principles based on density functional theory (DFT), this paper mainly studies the electronic properties of ML WS2, WSe2 and Wte2. We also study the stabilities of three ML structures, the changes of Raman spectra and the movement of Raman peaks under biaxial tensile and compressive strains. Under the control of strain not only does the bandgap changes, but also the band properties shift between the direct bandgap and the indirect bandgap. With the increase of strain, bond length and bond angle change in the opposite trend. At the same time, we also studied the phonon dispersion relations of WX2 under different strains. We found that three structures showed good thermodynamic stabilities under the tensile strain (1–10%). When the compressive strain is 2%, one of the acoustic modes of WS2 or Wse2 becomes imaginary at [Formula: see text] point, which indicates the structural instability. When tensile strain Raman summit blueshifts and when compressive strains, the redshift occurs.

scholarly journals Writing of strain-controlled multiferroic ribbons into MnWO4

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shingo Toyoda ◽  
Manfred Fiebig ◽  
Lea Forster ◽  
Taka-hisa Arima ◽  
Yoshinori Tokura ◽  
...  
Keyword(s):  
Physical Properties ◽  
Harmonic Generation ◽  
Domain Walls ◽  
Second Harmonic ◽  
Physical Nature ◽  
Electric Polarization ◽  
Structural Defects ◽  
Magnetic Memory ◽  
Low Dimensional ◽  
Second Harmonic Generation Imaging

AbstractLocal and low-dimensional structures, such as interfaces, domain walls and structural defects, may exhibit physical properties different from the bulk. Therein, a wide variety of local phases were discovered including conductive interfaces, sheet superconductivity, and magnetoelectric domain walls. The confinement of combined magnetic and electric orders to spatially selected regions may be particularly relevant for future technological applications because it may serve as basis of electrically controllable magnetic memory devices. However, direct observation of magnetoelectric low-dimensional structures cannot readily be done partly because of the lack of experimental techniques locally probing their physical nature. Here, we report an observation of multiferroic ribbon-like domains in a non-multiferroic environment in MnWO4. Using optical second harmonic generation imaging, we reveal that a multiferroic phase is stabilized by locally generated strain while the bulk magnetic structure is non-multiferroic. We further find that the confined multiferroic state retains domains with different directions of electric polarization and we demonstrate deterministic writing of a multiferroic state embedded in a non-multiferroic environment.

Monte Carlo Modeling of Heat Generation in Electronic Nanostructures

2002 ◽  
Author(s):  
Eric Pop ◽  
Sanjiv Sinha ◽  
Kenneth E. Goodson
Keyword(s):  
Monte Carlo ◽  
Electric Field ◽  
Heat Generation ◽  
Microscopic Analysis ◽  
Simulation Method ◽  
Transfer Rates ◽  
Scattering Rate ◽  
Energy Dependent ◽  
Non Equilibrium ◽  
Mc Method

This work develops a Monte Carlo (MC) simulation method for calculating the heat generation rate in electronic nanostructures. Electrons accelerated by the electric field scatter strongly with optical phonons, yet heat transport in silicon occurs via the faster acoustic modes. The MC method incorporates the appropriate energy transfer rates from electrons to each phonon branch. This accounts for the non-equilibrium energy exchange between the electrons and phonon branches. Using the MC method with an electron energy-dependent scattering rate intrinsically accounts for the non-locality of the heat transfer near a strongly peaked electric field. This approach provides more information about electronically generated heat at nanoscale dimensions compared to traditional macroscopic field-dependent methods. The method has applications in any region of high spatial or temporal non-equilibrium between electrons and phonons, and particularly facilitates careful microscopic analysis of heating in a nanoscale transistor.

Effects of Moisture Content and Soil Additions on Physical Properties and Transport Phenomena for Compost Windrow Design

2007 ◽  
Author(s):  
Alexandra C Srebro ◽  
Krystyna A Malinska ◽  
Eric D White ◽  
Joseph M Perez ◽  
Tom L Richard
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Transport Phenomena

The Photometric Properties of the Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 365-377 ◽  
Author(s):  
B. Hauck
Keyword(s):  
Physical Properties ◽  
Ap Stars

The Ap stars are numerous - the photometric systems tool It would be very tedious to review in detail all that which is in the literature concerning the photometry of the Ap stars. In my opinion it is necessary to examine the problem of the photometric properties of the Ap stars by considering first of all the possibility of deriving some physical properties for the Ap stars, or of detecting new ones. My talk today is prepared in this spirit. The classification by means of photoelectric photometric systems is at the present time very well established for many systems, such as UBV, uvbyβ, Vilnius, Geneva and DDO systems. Details and methods of classification can be found in Golay (1974) or in the proceedings of the Albany Colloquium edited by Philip and Hayes (1975).

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Sign in / Sign up

Export Citation Format

Share Document