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 ${\mathrm{IrTe}}_{2}$ measured using torque magnetometry at low temperatures down to 0.4 K and in high magnetic fields up to 33 T. ${\mathrm{IrTe}}_{2}$ undergoes a major structural transition around $\ensuremath{\sim}283(1)\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ 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 $1{m}_{e}$), 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 ${\mathrm{IrTe}}_{2}$.