Effect of Anisotropy of Elastic Energy on the Electron–Phonon Drag and Temperature Dependences of Thermal EMF in Potassium Crystals at Low Temperatures

2019 ◽  
Vol 120 (11) ◽  
pp. 1033-1039 ◽  
Author(s):  
I. I. Kuleev ◽  
I. G. Kuleev
Keyword(s):  
Elastic Energy ◽  
Low Temperatures ◽  
Phonon Drag ◽  
Thermal Emf ◽  
Temperature Dependences

Diameter and Temperature Dependences of Phonon-Drag Magnetothermopower in Bismuth Nanowires

2013 ◽  
Vol 1490 ◽  
pp. 133-138
Author(s):  
Naomi Hirayama ◽  
Akira Endo ◽  
Naomichi Hatano
Keyword(s):  
Size Effect ◽  
Low Temperatures ◽  
Theoretical Calculations ◽  
Peak Height ◽  
The Other ◽  
High Magnetic Fields ◽  
Phonon Drag ◽  
Phonon Modes ◽  
Temperature Dependences ◽  
Bismuth Nanowires

ABSTRACTWe present theoretical calculations of the phonon-drag contribution to the Nernst thermoelectric power Syx in Bismuth nanowires. We investigate the thermopower Syx with diameters L ranging from 22 to 900 nm at low temperatures (0.1 - 4.0 K) and high magnetic fields (up to 16 T). We find that the peak of thermopower Syx around 14.75 T exhibits the size effect in two different ways: for wires with L≥200 nm, the peak height increases with decreasing L; for wires with L<200 nm, on the other hand, the peak height rapidly decreases with decreasing L. The dependence is accounted for by considering the contributions of discrete quantized phonon modes. We also discuss the temperature dependence of Syx.

Anomaly of Nuclear Quadrupole Relaxation in Cu2O Prepared at Low Temperatures

1986 ◽  
Vol 41 (1-2) ◽  
pp. 382-385 ◽  
Author(s):  
J. Kasprzak ◽  
J. Lus ◽  
J. Pietrzak
Keyword(s):  
Temperature Dependence ◽  
Cuprous Oxide ◽  
Thermal Processing ◽  
Low Temperatures ◽  
Room Temperature ◽  
Quadrupole Relaxation ◽  
Temperature Dependences ◽  
Powder Samples ◽  
Nuclear Quadrupole ◽  
Nuclear Quadrupole Relaxation

The 63Cu and 65Cu NQR transitions in powder samples of cuprous oxide have been investigated from 77 to 500 K and at room temperature after annealing up to 1100 K Significant differences in T1 , NQR linewidth Δv, and their temperature dependences were found among the samples prepared in different ways. For C u20 samples obtained in low temperatures (below 380 K), the temperature dependence of T1 below 380 K is o f activation character with Ea = 0.07 eV. These results are interpreted in terms of an electron hopping mechanism. Thermal processing of these samples permits to obtain irreversible electronic state and then the spectroscopic parameters are the same as for the samples obtained in high temperatures (above 1320 K).

scholarly journals Far-infrared continuum absorption of forsterite and enstatite at low temperatures

2019 ◽  
Vol 625 ◽  
pp. A61
Author(s):  
Harald Mutschke ◽  
Pierre Mohr
Keyword(s):  
Low Temperatures ◽  
Optical Constants ◽  
Laboratory Data ◽  
Measurement Data ◽  
Far Infrared ◽  
Absorption Bands ◽  
Lack Of Information ◽  
Temperature Dependences ◽  
Cold Dust ◽  
Infrared Continuum

Context. The far-infrared continuum opacity of cold dust is an important quantity for the study of debris disks in planetary systems and of protoplanetary disks. Forsterite and enstatite are considered to be the most abundant crystalline dust species in such environments. Aims. The optical constants of these minerals at wavelengths above 80 μm, which govern the opacity, and their temperature dependence are poorly known. Our aim is to fill in this lack of information with new laboratory data. Methods. We present spectroscopic transmission measurements on forsterite and enstatite single crystals of up to 10 mm thickness at wavelengths between 45 and 500 μm and for temperatures down to 10 K. We compare our results to literature data originating from powder transmission and from reflection spectroscopy. Results. The imaginary parts of the refractive indices calculated from the measurements show very strong temperature dependences, which to that extent are not seen in reflection-based data or in powder measurement data. The temperature dependences can be described by a simple theoretical model taking the contributions of single-phonon absorption and phonon difference processes into account. We also observe, for the first time, enstatite absorption bands at 87.5 μm and 116.6 μm wavelengths. Conclusions. The single-crystal optical constants of forsterite and enstatite predict an extremely small submillimeter opacity of crystalline silicate dust at low temperatures, which would make these particles almost invisible in the thermal radiation of cold dust. Thus, it is important to understand why absorption measurements with mineral powders resulted in much higher opacity values.

The Effect of Light Soaking on the Photoconductivity Response in A-SI:H

1986 ◽  
Vol 70 ◽  
Author(s):  
Qiu Changhua ◽  
Wu Wenhao ◽  
Zhao Shifu ◽  
Han Daxing
Keyword(s):  
Steady State ◽  
Response Time ◽  
Fermi Level ◽  
Low Temperatures ◽  
Deep Traps ◽  
Temperature Dependences ◽  
The Difference ◽  
Shallow Traps ◽  
Photoconductivity Response ◽  
Effect Of Light

ABSTRACTThe temperature dependences of response time tr and steady state photoconductivity (PC) were used to deduce the DOS at energies above the dark Fermi level. The tr and PC of annealled state A and light soaked state B were measured from 115K to 300K. Light soaking causes degradation of PC. Compared with state A, the PC response of state B is faster at low temperatures, but is slower at high temperatures. The difference between state A and state B was interpreted by a decrease of shallow traps and an increase of deep traps.

Quadrupole Coupling in Ammonium Metaperiodate at Low Temperature

2002 ◽  
Vol 57 (8) ◽  
pp. 661-662 ◽  
Author(s):  
S. L. Segel ◽  
R. J. C. Brown ◽  
E. E. Ylinen ◽  
L. P. Ingman ◽  
T. J. Bastow
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Quadrupole Coupling ◽  
Temperature Dependences ◽  
Nuclear Quadrupole

The temperature dependences of the 127I nuclear quadrupole coupling in NH4IO4 and in ND4IO4 are reported. In each salt, the quadrupole coupling decreases to a very small value at low temperatures, and in the case of ND4IO4 passes through zero and changes sign at 87 K.

Thermal emf in a bipolar semiconductor with phonon drag of carriers

2000 ◽  
Vol 34 (9) ◽  
pp. 1052-1053 ◽  
Author(s):  
A. Konin ◽  
R. Raguotis
Keyword(s):  
Phonon Drag ◽  
Thermal Emf ◽  
Bipolar Semiconductor

scholarly journals Туннельная проводимость и туннельное магнитосопротивление пленок Fe-SiO: корреляция магнитотранспортных и магнитных свойств

2019 ◽  
Vol 61 (7) ◽  
pp. 1262
Author(s):  
Д.А. Балаев ◽  
А.Д. Балаев
Keyword(s):  
Activation Energy ◽  
Electrical Resistance ◽  
Low Temperatures ◽  
Magnetic Method ◽  
Tunnel Mechanism ◽  
Giant Magnetoresistive Effect ◽  
Temperature Dependences ◽  
Magnetoresistive Effect ◽  
Dielectric Region ◽  
Good Agreement

The paper presents the results of a study of the electrical properties of a system of nanogranular amorphous Fe-SiO films with a SiO concentration from 0 to 92 Vol.%. For samples with a low SiO content, metallic conductivity takes place. With an increase of the dielectric content, a concentration transition of conduction from the metallic regime to the tunnel regime at a dielectric concentration x  0.6 is observed. At the same concentration, a transition ferromagnet - superparamagnet occurs, which was previously investigated by the magnetic method. For compositions corresponding to the dielectric region, the temperature dependences of the electrical resistance (T) follow the law (T) ~ exp(2(С/kT)1/2), which is typical for the tunnel mechanism of conductivity. Estimation of the sizes of metal granules from the values of the tunneling-activation energy C showed a good agreement with the sizes obtained earlier from the analysis of magnetic properties. In the dielectric range of the compositions, a giant magnetoresistive effect was obtained, reaching 25% at low temperatures.

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