Fermi arcs versus hole pockets: Periodization of a cellular two-band model

Hall effect and resistivity measurements have been made in the temperature range 4.2–360 °K on several samples of n-type GaAs grown under oxygen atmosphere and without any other intentional dopings. The principal shallow donor in this material is considered to be Si. All samples exhibited impurity-band conduction at low temperature. Electron concentrations in the conduction band were calculated, using a two-band model, and then fitted to the usual equation expressing charge neutrality. A value of 2.3 × 10−3 eV was obtained for the ionization energy of the donors, for donor concentration ranging from 5 × 1015 cm−3 to 2 × 1016 cm−3. The conduction in the impurity band was of the hopping type for these concentrations. A value of 3.5 × 1016 cm−3 was obtained for the critical transition concentration of the impurity-band conduction to the metallic type.

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Properties of the superconducting state in a two-band model

Physical Review B ◽

10.1103/physrevb.71.054501 ◽

2005 ◽

Vol 71 (5) ◽

Cited By ~ 106

Author(s):

E. J. Nicol ◽

J. P. Carbotte

Keyword(s):

Superconducting State ◽

Band Model ◽

Two Band Model

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ENERGY BAND OVERLAPPING IN HIGH-Tc SUPERCONDUCTORS

Modern Physics Letters B ◽

10.1142/s0217984996001681 ◽

1996 ◽

Vol 10 (30) ◽

pp. 1483-1490 ◽

Cited By ~ 10

Author(s):

M. MORENO ◽

R. M. MÉNDEZ-MORENO ◽

M. A. ORTIZ ◽

S. OROZCO

Keyword(s):

Weak Coupling ◽

Cuprate Superconductors ◽

Weak Coupling Limit ◽

Band Model ◽

Coupling Constant ◽

High Tc Superconductors ◽

Energy Bands ◽

Effective Coupling ◽

High Tc ◽

Two Band Model

Multi-band superconductors are analyzed and the relevance of overlapping energy bands to the high-T c of these materials is studied. Within the BCS framework, a two band model with generalized Fermi surface topologies is developed. Values of the overlapped occupancy parameters for typical cuprate superconductors are obtained as a function of the ratio R and the effective coupling constant, λ, in the weak-coupling limit. The overlap scale is of the order or lower than the cutoff (Debye) energy. The typical behavior of the isotope effect is obtained. As these superconductors have transition temperatures above the phonon barrier, the results of this approach are important to the generic understanding of the high-T c superconducting mechanism.

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Bound states of two holes in the double-layer two-dimensional two-band model

Physica C Superconductivity ◽

10.1016/0921-4534(94)92333-7 ◽

1994 ◽

Vol 235-240 ◽

pp. 2223-2224 ◽

Cited By ~ 3

Author(s):

A. Mishima

Keyword(s):

Double Layer ◽

Bound States ◽

Band Model ◽

Two Dimensional ◽

Two Band Model

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Thermoelectric Power of the Liquid Sn—Te Alloy

Zeitschrift für Naturforschung A ◽

10.1515/zna-1982-1004 ◽

1982 ◽

Vol 37 (10) ◽

pp. 1127-1131 ◽

Cited By ~ 2

Author(s):

D. H. Kurlat ◽

M. Rosen

Keyword(s):

Thermoelectric Power ◽

Hard Sphere ◽

Stoichiometric Composition ◽

Band Model ◽

Liquid Alloys ◽

Sphere Approximation ◽

The Difference ◽

Predicted Values ◽

Experimental Values ◽

Two Band Model

The Seebeck coefficient (S) of Sni1-x- Tex liquid alloys was measured as a function of concentration and temperature. For 0 ≦ x <0.45 the behaviour is metallic; S values are small and negative, rising linearly with temperature. The predicted values of Ziman's theory when using the hard sphere approximation disagree with the experimental ones. The change in sign occurs for 0.45. For x = 0.5 (stoichiometric composition) the thermoelectric power decreases linearly with temperature. This fact is explained assuming a two-band model. For x ≧ 0.6 the liquid alloy becomes more semiconducting and presents a maximum in the isotherms of S for x = 0.65. For the excess tellurium concentration range we have calculated the difference EF - EV and γ/kB, assuming a S(1/T) law. The experimental values are compared with those of Dancy and Glazov.

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