Fermi surface and light quasi particles in hourglass nodal chain metal-ReO.

Quantum oscillations (QOs) in magnetic torque and electrical resistivity were measured to investigate the electronic structure of-ReO, a candidate hourglass nodal chain (NC) metal (Dirac loop chain metal). All the de Haas-van Alphen oscillation branches measured at 30 mK in magnetic fields of up to 17.5 T were consistent with first-principles calculations predicting four Fermi surfaces (FSs). The small-electron FS of the four FSs exhibited a very small cyclotron mass, 0.059 times that of the free electrons, which is likely related to the linear dispersion of the energy band. The consistency between the QO results and band calculations indicates the presence of the hourglass NC predicted for-ReOin the vicinity of the Fermi energy.