Quantum oscillations in the linear chain of coupled orbits: the organic metal with two cation layers theta-(ET)(4)CoBr(4)(C(6)H(4)Cl(2))

TL;DR

This paper derives analytical formulas for de Haas-van Alphen oscillations in a linear chain of coupled 2D orbits, accounting for chemical potential oscillations, and compares the results with experimental spectra of an organic metal.

Contribution

It provides a systematic derivation of oscillation formulas considering chemical potential oscillations and explains non-LK behavior of certain orbits in a specific organic metal.

Findings

Basic and magnetic breakdown orbits fit semiclassical models

Forbidden orbit amplitude described by non-LK equation

Non-monotonic field and temperature dependence observed

Abstract

Analytical formulae for de Haas-van Alphen (dHvA) oscillations in linear chain of coupled two-dimensional (2D) orbits (Pippard's model) are derived systematically taking into account the chemical potential oscillations in magnetic field. Although corrective terms are observed, basic (alpha) and magnetic breakdown-induced (beta and 2beta - alpha) orbits can be accounted for by the Lifshits-Kosevich (LK) and Falicov-Stachowiak semiclassical models in the explored field and temperature ranges. In contrast, the 'forbidden orbit' beta - alpha amplitude is described by a non-LK equation involving a product of two classical orbit amplitudes. Furthermore, strongly non-monotonic field and temperature dependence may be observed for the second harmonics of basic frequencies such as 2alpha and the magnetic breakdown orbit beta + alpha, depending on the value of the spin damping factors. These features are in agreement with the dHvA oscillation spectra of the strongly 2D organic metal theta- theta-(ET)(4)CoBr(4)(C(6)H(4)Cl(2)).