Random walks and magnetic oscillations in compensated metals

Abstract

The field- and temperature-dependent de Haas-van Alphen oscillations spectrum is studied for an ideal two-dimensional compensated metal whose Fermi surface is made of a linear chain of successive orbits with electron and hole character, coupled by magnetic breakdown. We show that the first harmonics amplitude can be accurately evaluated on the basis of the Lifshits-Kosevich (LK) formula by considering a set of random walks on the orbit network, in agreement with the numerical resolution of semi-classical equations. Oppositely, the second harmonics amplitude does not follow the LK behavior and vanishes at a critical value of the field-to-temperature ratio which depends explicitly on the relative value between the hole and electron effective masses.Comment: 9 pages, 10 figures. Submitted to Physical Review

Three-quarter Dirac points, Landau levels, and magnetization in α−(BEDT−TTF)2I3

“…Recently, we have studied the de Haas van Alphen (dHvA) oscillation 15 in the tight-binding model for (TMTSF) 2 NO 3 where electron and hole pockets coexist [27][28][29] . In that system the dHvA oscillation has been usually studied in the phenomenological theory of magnetic breakdown 30,31 and the Lifshitz and Kosevich (LK) formula 32,33 . The dHvA oscillation and the LK formula [34][35][36][37] are explained in Appendix B.…”

Quantum oscillations in coupled orbits networks of (BEDT-TTF) salts with tris(oxalato)metallate anions

“…1(b) and (c), respectively) compensated orbits are observed. In contrast with the above mentioned case, oscillations of the chemical potential are significantly damped [12,13] and the LifshitzKosevich formalism [14][15][16] holds.…”

“…2(b). Extensive calculation of the Fourier amplitude, based on combinatorial analysis, has been reported in [13]. Limiting ourselves to η orbits with frequency 1 F made of at most three individual orbits, yields: where p = exp(-B 0 /2B) is the tunneling probability and B 0 is the MB field.…”

“…Limiting ourselves to η orbits with frequency 1 F made of at most three individual orbits, yields: where p = exp(-B 0 /2B) is the tunneling probability and B 0 is the MB field. B B values, hence large tunneling probability, orbits 2e h + and 2 e h + can contribute substantially, leading to non-LifshitzKosevich behavior (i.e., apparent temperature-dependent effective mass) [13]. In addition, 1 A is strongly dependent on the relative values of the spin damping factors which are governed by the product .…”

“…with, taking into account the symmetry factors (1 and 2 for 1 (2) h and 2 (1) e h + , respectively), 13 for the one-dimensional chain, are needed to get a more deeper insight on the oscillatory behavior of two-dimensional networks of compensated orbits. Nevertheless, it can be considered that for large enough Dingle temperature and MB gaps only orbits with the smallest effective masses can significantly contribute to the data.…”