Frequency combinations in the magnetoresistance oscillations spectrum of a linear chain of coupled orbits with a high scattering rate

TL;DR

This study investigates the magnetoresistance oscillations in an organic metal with a complex Fermi surface, revealing unexpected frequency combinations that challenge existing theoretical models.

Contribution

It provides detailed experimental data on oscillation spectra in a high scattering rate regime, highlighting discrepancies with current quantum interference and semiclassical theories.

Findings

Multiple frequency combinations observed in the spectrum.

Effective masses and Dingle temperatures do not match existing models.

High scattering rate reduces chemical potential oscillations.

Abstract

The oscillatory magnetoresistance spectrum of the organic metal (BEDO)$_5$Ni(CN)$_4\cdot$3C$_2$H$_4$(OH)$_2$ has been studied up to 50 T, in the temperature range from 1.5 K to 4.2 K. In high magnetic field, its Fermi surface corresponds to a linear chain of quasi-two-dimensional orbits coupled by magnetic breakdown (MB). The scattering rate consistently deduced from the data relevant to the basic $\alpha$ and the MB-induced $\beta$ orbits is very large which points to a significant reduction of the chemical potential oscillation. Despite of this feature, the oscillations spectrum exhibits many frequency combinations. Their effective masses and (or) Dingle temperature are not in agreement with either the predictions of the quantum interference model or the semiclassical model of Falicov and Stachowiak.