Low Temperature Physics: 41, 537 (2015); https://doi.org/10.1063/1.4927316
Fizika Nizkikh Temperatur: Volume 41, Number 7 (July 2015), p. 691-698    ( to contents , go back )

Galvanomagnetic phenomena in organic conductors under topological phase transition

O. Galbova1, V.G. Peschansky2,3, and D.I. Stepanenko2

1Faculty of Natural Sciences and Mathematics, Institute of Physics, P.O.Box 162, Skopje 1000, Republic of Macedonia

2B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine

3V.N. Karazin National University, Kharkov 61077, Ukraine

Received March 17, 2015


The magnetoresistance of layered conductors with a multisheeted Fermi surface (FS) is studied theoretically under conditions of Lifshitz topological transition, where the FS topology may change in response to external effects on the conductor, such as pressure or impurity atom doping. Using as an example the Fermi surface consisting of a cylinder and two planes, slightly corrugated along the projection of the momentum along the normal to the layers, we analyze the dependence of kinetic coefficients on strong magnetic field Н, where the cyclotron frequency wc of the conduction electrons is much higher than the frequency of their collisions 1/t. In the immediate vicinity of the topological transition, where the distance between various sheets of the FS becomes small, the electron, affected by magnetic breakdown can transfer from one sheet of the FS to another with the probability w. In this case a field-induced quadratic increase in resistance to the electric current across the layers in the absence of magnetic breakdown (w = 0) is changed by a linear dependence on H when wg = 1/wct. At (1 – w)≤g the linear growth in interlayer resistance with H reaches saturation. The Hall field depends substantially on the probability of magnetic breakdown, but its asymptote in the case of wct >> 1 is independent of t for all values of w. At w = 1 the quasi-planar sheets of the Fermi surface touch the corrugated cylinders, and with a further action of the perturbation on the conductor there occurs a break of a flat sheet along the line of contact. As a result separate sections of the flat sheet of FS together with the cut halves of the corrugated cylinder form finally a new corrugated cylinder, the sign of charge carriers being reversed. This is not the only way of the Lifshitz topological transition. Investigation of the Hall effect will provide additional important information on the nature of changes in the topological structure of electron energy spectrum under phase transition.

PACS: 72.15.Gd Galvanomagnetic and other magnetotransport effects;
PACS: 74.70.Kn Organic superconductors.

Key words: Fermi surface, magnetic breakdown, Hall effect.

Published online: May 25, 2015

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