Aperiodic quantum oscillations of particle-hole asymmetric Dirac cones

We report experimental measurements and theoretical analysis of Shubnikov-de Haas (SdH) oscillations in a Dirac cone system: the alpha-(BEDT-TTF)(2)I-3 organic metal under hydrostatic pressure. The measured SdH oscillations reveal anomalies at high magnetic fields B where the 1/B oscillations periodicity is lost above 7 T. We interpret these unusual results within a theoretical model that takes into account intrinsic distortions of the alpha-(BEDT-TTF)(2)I-3 Dirac cones such as a parabolic particle-hole asymmetric correction. Others possible causes, such as a cone tilting or a Zeeman effect, are carefully ruled out. The observations are consistent among alpha-(BEDT-TTF)(2)I-3 samples with different Fermi levels. Copyright (C) EPLA, 2017