Non-Lifshitz–Kosevich field- and temperature-dependent amplitude of quantum oscillations in the quasi-two dimensional metal θ-(ET)4ZnBr4(C6H4Cl2)

According to band structure calculations, the Fermi surface of the quasi-two dimensional metal -(ET)4ZnBr4(C6H4Cl2) illustrates the linear chain of coupled orbits model. Accordingly, de Haas–van Alphen oscillations spectra recorded in pulsed magnetic field of up to 55 T evidence many Fourier components, the frequency of which are linear combinations of the frequencies relevant to the closed and the magnetic breakdown orbits. The field and temperature dependence of their amplitude are quantitatively accounted for by analytic calculations including, beyond the Lifshitz–Kosevich formula, second-order terms in damping factors due to the oscillation of the chemical potential as the magnetic field varies. Whereas these second-order terms are negligible for the orbits , and , they are solely responsible for the 'forbidden orbit' and its harmonic and have a significant influence on Fourier components such as and , yielding strongly non-Lifshitz–Kosevich behaviour in the latter case.