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Study of quantum oscillations in an organic conductor up to 81 T

The newest double coil system recently put into operation in Toulouse ’only’ generates magnetic fields up to 81.3 T, i.e., smaller than the american world record (100.75 T generated at the NHMFL Los Alamos), but it offers a record field duration of 10.2 ms above 70 T, reducing eddy current problems and facilitating high quality data acquisition of any physical parameter rapidly varying in magnetic field. First experiments on an organic conductor have shown an excellent signal-to-noise level, which is close to that of standard 60-T magnets of the LNCMI.

High frequency de Haas-van Alphen oscillations of the organic metal \theta-(ET)4ZnBr4(C6H4Cl2) have been studied in pulsed magnetic fields up to 81 T delivered by the double-coil magnet recently designed at the LNCMI-Toulouse. The exceptionally long-decay time of the pulse allowed determining field-dependent amplitudes of Fourier components with frequencies up to several kT. The Fourier spectrum is in agreement with the model of a linear chain of coupled orbits: all the observed frequencies are linear combinations of the frequencies linked to the basic \alpha orbit and to the magnetic-breakdown orbit \beta. This work constitutes the first published experimental study made in Europe using non-destructive magnetic fields above 80 T.

Figure: (a) Temporal profiles of the highest non-destructive magnetic field pulses generated at different pulsed-field facilities (October 2012) and (b) duration time above 70 T versus maximum magnetic field of these pulses, (c) quantum oscillations of the organic metal \theta-(ET)4ZnBr4(C6H4Cl2) up to 81 T and (d) corresponding Fourier analysis.

Recently, a comprehensive study of the field- and temperature-dependent amplitudes of the quantum oscillations has also been made on the parent compound \theta-(ET)4CoBr4(C6H4Cl2) in magnetic fields up to 60 T. Analytical formulas derived for the first time on that occasion allowed to quantitatively account for the field- and temperature-dependent amplitude of the oscillations spectra for this widespread textbook Fermi surface topology.

References:

[1] High-frequency magnetic oscillations of the organic metal \theta-(ET)4ZnBr4(C6H4Cl2) in pulsed magnetic field of up to 81 T, J. Béard et al, Eur. Phys. J. Appl. Phys. 59, 30201 (2012).

[2] Quantum oscillations in the linear chain of coupled orbits: The organic metal with two cation layers \theta-(ET)4CoBr4(C6H4Cl2), A. Audouard et al, EPL 97, 57003 (2012).

[3] Actualité de l’INP "L’impulsion de champ magnétique à 80 teslas la plus longue au monde"

Contact: Alain Audouard