de Haas-van Alphen oscillations and anomalous Hall effect in topological nodal line semimetal Ni0.5Co0.5Se

Here, we present a systematic study of de Haas-van Alphen oscillations (dHvA), topological phase, and anomalous Hall effect (AHE) of Ni0.5Co0.5Se single crystal. Low-temperature longitudinal resistivity ρxx(T) under different magnetic fields exhibits an upturn, indicative of a semimetallic phase. Fitting of the zero-field ρxx(T) data with the Bloch-Gruneisen-Mott model including Kondo resistivity term reveals multiple scattering mechanisms, which is substantiated by the deviation from Kohler’s rule of the magnetoresistance curves. At T = 2 K and low magnetic fields, the observed cusp-like features indicate weak antilocalization effect, quantitatively described using a modified Hikami-Larkin-Nagaoka equation. Temperature dependent magnetization (M-T) curves and magnetic field dependent isothermal magnetization (M-B) curves reveal the existence of weak ferromagnetic phase at very low temperatures. The weak field magnetoconductivity data follows the-ln(B) dependency and the observed strong high field dHvA oscillations in (M-B) curves, provide the evidence of non-zero Berry phase, confirms the non-trivial band topology. These signatures indicate that Ni0.5Co0.5Se is a topological nodal line semimetal. In Hall resistivity data, significant AHE is observed at 2 K to 5 K and the linear behavior of the anomalous Hall resistivity (ρAxy) with ρxx signifies that the extrinsic skew scattering mechanism contributes to AHE in Ni0.5Co0.5Se.