Aperiodic Quantum Oscillations of Particle-hole Asymmetric Dirac Cones

Since the 2000s, with the discovery of the graphene, the physics of the condensed matter faces the emerging of new materials having a linear dispersion relation: the Dirac materials. It is the case of the α-(BEDT-TTF)2I3 organic metal (afterward, denoted αI3), under high hydrostatic pressure (P>1,5GPa) [1]. In contrast to the case of purely 2D graphene on SiO2, the 3D bulk structure of αI3 allows to sound a physics much closer to the Dirac point. However, the coexistence of massive and Dirac fermions within the αI3 compound [2] makes this physics particularly complex, but also rich and surprising. The Shubnikov-de Haas oscillations (semi-classical oscillations of the magnetoresistance) in αI3, under high pressures and very low temperatures (about 2GPa and 200 mK) reveal anomalies. Indeed, if the periodic behavior in 1/B of these oscillations at low magnetic fields is well known and understood, it is not the case for the deviation from this behavior, which appears at higher magnetic fields (B>7T). We interpret these unusual results with an original theoretical model [3].

[1] Kobayashi A. and al., J. Phys. Soc. Jpn., 76 034711 (2007)
[2] Monteverde M. and al., Phys. Rev. B., 87 245110 (2013)
[3] arXiv:1711.00039 [cond-mat.mes-hall]