Fermi surface topology of the topological nodal-loop semimetal HfP2

Topological nodal-loop semimetals represent an important class of quantum materials and have attracted intense research interest due to their exotic topological states and transport phenomena. Hafnium phosphide (HfP 2 ) is a recently discovered nodal-loop semimetal and its transport properties have not been reported yet. Here, we grew HfP 2 single crystals by the chemical vapor transport method and report the magneto-transport properties under high magnetic fields up to 34.6 T. Pronounced Shubnikov-de Haas (SdH) oscillations with beating patterns were observed at low temperatures. These oscillations originate from two electron pockets and one hole pocket, as cross-confirmed by Hall effect analysis by a two-band model and first-principles calculations of the Fermi surface. Furthermore, the Landau fan diagram analysis for the electron pockets verifies the nontrivial Berry phase, which is consistent to Dirac-type band dispersion in HfP 2 . Our work provides systematic transport characterizations of HfP 2 crystals and sheds more light on the physical properties of topological nodal-loop semimetals.