Fermi surface of IrTe₂ in the valence-bond state as determined by quantum oscillations

We report the observation of the de Haas-van Alphen effect in IrTe₂ measured using torque magnetometry at low temperatures down to 0.4 K and in high magnetic fields up to 33 T. IrTe₂ undergoes a major structural transition around ∼283(1)K due to the formation of planes of Ir and Te dimers that cut diagonally through the lattice planes, with its electronic structure predicted to change significantly from a layered system with predominantly three-dimensional character to a tilted quasi-two-dimensional Fermi surface. Quantum oscillations provide direct confirmation of this unusual tilted Fermi surface and also reveal very light quasiparticle masses (less than 1me), with no significant enhancement due to electronic correlations. We find good agreement between the angular dependence of the observed and calculated de Haas-van Alphen frequencies, taking into account the contribution of different structural domains that form while cooling IrTe₂.