Physical Properties of the Pb1-xSnxTe Solid Solutions in the Vicinity of the Topological Phase Transition | Chapter 7 | Current Perspective to Physical Science Research Vol. 6

Semiconductor Pb1-xSnxTe solid solutions (PSTS) are well known as promising materials widely used in the IR electronics, thermoelectricity and other fields of science and technology. Recently, it has been found that these alloys in certain concentration ranges exhibit the properties characteristic of the new quantum objects of solid-state physics – topological crystalline insulators (TCIs), whose unique properties define new possibilities for practical use of these materials in spintronics, quantum computing and thermoelectricity. The fact that in PSTS, the band inversion near some composition xc leads to the emergence of the TCI states stimulates a detailed study of the behavior of the lattice, transport, and thermoelectric properties near xc. The goal of the studies presented here was to reveal effects accompanying the band inversion in PSTS by measuring the x-dependences of the heat capacity Cp, microhardness H, lattice thermal conductivity λ L electrical conductivity σ, charge carrier mobility μ H, the Hall coefficient RH, and the Seebeck coefficient S in the range x = (0.59 – 0.68), near the composition (x ~ 0.62) corresponding to the transition to an inversion  state at room temperature. It was established that the transition to the band inverted state is manifested through the appearance of peaks in the isotherms (T = 77-300 K) of  CP, H, σ, RH , μH, and S at x ~ 0.62. In the λL (X) isotherms, we observed two peaks near x =0.61 and x=0.63 and suggested that one peak corresponded to the band inversion point, and the other peak – to a structural self-organization process in the crystal lattice.

Author(s) Details:

E. I. Rogacheva,
National Technical University, Kharkiv Polytechnic Institute, 2 kyrpychova St., 61002 Kharkiv, Ukraine.

G. O. Nikolaenko,
National Technical University, Kharkiv Polytechnic Institute, 2 kyrpychova St., 61002 Kharkiv, Ukraine.

O. N. Nashchekina,
National Technical University, Kharkiv Polytechnic Institute, 2 kyrpychova St., 61002 Kharkiv, Ukraine.

Please see the link here: https://stm.bookpi.org/CPPSR-V6/article/view/13254

Keywords: Pb1–xSnxTe, topological crystalline insulator, band inversion, heat capacity, microhardness, thermal conductivity, electrical conductivity, hall coefficient, charge carrier mobility, seebeck coefficient, self-organization

Description of the Transport Characteristics of Charge Carriers in Normal State Superconductor YBa2Cu3O7-1 | Chapter 6 | New Insights into Physical Science Vol.3

The general expressions based on the Fermi distribution of the free charge carriers are applied for estimation of the transport characteristics in superconductors at the temperature well above the superconducting phase transition temperature TC. The Hall-effect experimental results in the normal state of the superconductor YBa2Cu3O7- are not finally explained. On the ground of the randomly moving charge carriers there are presented the transport characteristics for both single type and two types of the charge carriers. The particular attention has been pointed to the Hall-effect measurement results of the high-TC superconductor YBa2Cu3O7-. It is at the first time derived the Hall coefficient expression for two type of highly degenerate charge carriers (electrons and holes) on the ground of the randomly moving charge carriers at the Fermi surface. It is shown that the Hall coefficient and other transport characteristics are determined by the ratio between the electron-like and hole-like density-of-states at the Fermi surface.

Author (s)  Details
Vilius Palenskis
Faculty of Physics, Vilnius University, Vilnius, Lithuania.

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