High-frequency magnetic oscillations of the organic metal θ-(ET)4ZnBr4(C6H4Cl2) in pulsed magnetic field of up to 81 T

De Haas-van Alphen oscillations of the organic metal θ -(ET) 4 ZnBr 4 (C 6 H 4 Cl 2 ) are studied in pulsed magnetic fields up to 81 T. The long decay time of the pulse allows determining reliable field-dependent amplitudes of Fourier components with frequencies up to several kiloteslas. The Fourier spectrum is in agreement with the model of a linear chain of coupled orbits. In this model, all the observed frequencies are linear combinations of the frequency linked to the basic orbit α and to the magnetic-breakdown orbit β .