Thermal Conductivity in the Two-Band Model of Superconducting Transition Metals Containing Nonmagnetic Impurities

1972 ◽  
Vol 6 (7) ◽  
pp. 2642-2647 ◽  
Author(s):  
Pramod Kumar ◽  
S. N. Gupta
Keyword(s):  
Thermal Conductivity ◽  
Transition Metals ◽  
Band Model ◽  
Superconducting Transition ◽  
Nonmagnetic Impurities ◽  
Two Band Model

The Electrical Resistivity, Thermal Conductivity, and Thermoelectric Power of Calcium from 30 K to 300 K

1975 ◽  
Vol 53 (5) ◽  
pp. 486-497 ◽  
Author(s):  
J. G. Cook ◽  
M. J. Laubitz ◽  
M. P. Van der Meer
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Band Structure ◽  
Large Deviations ◽  
Transport Properties ◽  
Thermoelectric Power ◽  
Band Model ◽  
Residual Resistance ◽  
Two Samples ◽  
Two Band Model

Data are presented for the thermal and electrical resistivity and thermoelectric power of two samples of Ca (having residual resistance ratios of 10 and 70) between 30 and 300 K. Large deviations from both Matthiessen's rule and the Wiedemann–Franz relationship are observed. The former are tentatively attributed to the presence of two distinct groups of carriers in Ca, and analyzed using the two band model. The latter deviations are interpreted as the effects of band structure. The thermoelectric power of Ca is large. In many respects the transport properties of Ca appear to be similar to those of the transition metals.

Te Substitution Effect in Low-Dimensional Superconductor NbSe2-xTex (x = 0, 0.1, 0.2)

2007 ◽  
Vol 546-549 ◽  
pp. 2019-2022 ◽  
Author(s):  
Ejaz Ahmed ◽  
Lin Jun Li ◽  
Cheng He ◽  
Hong Tao Wang ◽  
Jing Qin Shen ◽  
...  
Keyword(s):  
Upper Critical Field ◽  
Sharp Decrease ◽  
Substitution Effect ◽  
Vapor Transport ◽  
Band Model ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Low Dimensional ◽  
Two Band Model ◽  
Transport Method

The Te doped NbSe2-xTex (x=0, 0.10, 0.20) single crystals were prepared by vapor transport method and the variations of structure and superconducting properties with Te content were studied. It is found that the Te substitution increases the degree of disorder and causes sharp decrease of superconducting transition temperature (Tc). The temperature dependence of upper critical field (Hc2) of pure NbSe2 crystal can be fitted by the two-band model, and the effect of Te substitution on Hc2(T) is discussed.

High-Temperature Transport Properties of Palladium

1972 ◽  
Vol 50 (3) ◽  
pp. 196-205 ◽  
Author(s):  
M. J. Laubitz ◽  
T. Matsumura
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Large Deviations ◽  
Thermoelectric Power ◽  
The Other ◽  
Band Model ◽  
Experimental Systems ◽  
Two Band Model ◽  
Pure Palladium

The thermal conductivity, electrical resistivity, and absolute thermoelectric power of pure palladium have been determined from 90 to 1300 K in two experimental systems of proven reliability. These properties are compared with the sparse available literature data, and show large deviations from them, particularly for the thermal conductivity at high temperatures. The results are also analyzed in terms of a simple two-band model, where one band contains the carriers, and the other acts as a trap into which phonons scatter the carriers. When the recent density of states values of Mueller et al. are used, the model predicts correctly the temperature variation of the electrical resistivity, and reasonably well its observed magnitude and the observed Wiedemann–Franz ratio. However, the model fails badly in respect to the absolute thermoelectric power, predicting values twice as large as the observed ones. Modifications to the model are suggested which may improve the fit between the predicted and observed values.

THE THERMOELECTRIC POWER OF V3X COMPOUNDS

1963 ◽  
Vol 41 (10) ◽  
pp. 1542-1546 ◽  
Author(s):  
M. P. Sarachik ◽  
G. E. Smith ◽  
J. H. Wernick
Keyword(s):  
Thermoelectric Power ◽  
Intermetallic Compounds ◽  
Conduction Band ◽  
Room Temperature ◽  
Band Model ◽  
Transition Temperatures ◽  
Superconducting Transition ◽  
Increasing Functions ◽  
Two Band Model

The thermoelectric powers of the intermetallic compounds V3Ge, V3Si, V3Ga, and V3Sn have been measured from their superconducting transition temperatures to room temperature. It is found that the thermoelectric coefficients are all positive and about 10 μv/° K at room temperature. The coefficients for V3Si, V3Ga, and V3Sn are monotonically increasing functions of the temperature, whereas for V3Ge there is a pronounced maximum at about 60° K. The results are discussed in terms of a two-band model consisting of a conduction band and a d-band.

scholarly journals Temperature-Dependent s± ↔ s++ Transitions in the Multiband Model for Fe-Based Superconductors with Impurities

Symmetry ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 323 ◽  
Author(s):  
V. Shestakov ◽  
M. Korshunov ◽  
O. Dolgov
Keyword(s):  
Narrow Range ◽  
Impurity Scattering ◽  
Band Model ◽  
Temperature Dependent ◽  
Clean Limit ◽  
Scattering Rate ◽  
Nonmagnetic Impurities ◽  
Multiband Model ◽  
Critical Temperature Tc ◽  
Two Band Model

We study the dependence of the superconducting gaps on both the disorder and the temperature within the two-band model for iron-based materials. In the clean limit, the system is in the s± state with sign-changing gaps. Scattering by nonmagnetic impurities leads to the change of the sign of the smaller gap, resulting in a transition from the s± to the s++ state with the sign-preserving gaps. We show here that the transition is temperature-dependent. Thus, there is a line of s±→s++ transition in the temperature–disorder phase diagram. There is a narrow range of impurity scattering rates, where the disorder-induced s±→s++ transition occurs at low temperatures, but then the low-temperature s++ state transforms back to the s± state at higher temperatures. With increasing impurity scattering rate, the temperature of such s++→s± transition shifts to the critical temperature Tc, and only the s++ state is left for higher amounts of disorder.

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