Topological nodal line features in NiSe semimetal: Insights from electronic transport and density functional theory studies

The linear band touchings at one-dimensional lines or rings that characterize a nodal line semimetal phase have created much interest in research as they may find use in the next generation of low-dissipation electronics and spintronics. Here we demonstrated the presence of multiple scattering processes including electron-phonon $(e\text{\ensuremath{-}}p)$ and Mott's interband scattering within a single crystal of nickel selenide (NiSe) using temperature-dependent resistivity data fitted to Bloch-Gruneisen-Mott formula. Multiple scattering mechanisms were further validated from the observation of transverse magnetoresistance (MR) data that displayed a well scaled in extended Kohler's rule and a deviation from Kohler's rule. Temperature-dependent resistivity at different magnetic fields indicate topological semimetallic nature of NiSe. The observed negative magnetoconductivity data fitted to the Hikami-Larkin-Nagaoka equation describes weak antilocalization. The weak field magnetoconductivity follows the $\ensuremath{-}\mathrm{ln}(B)$ scaling behavior, indicating the topological nodal line feature. The density functional theory (DFT) calculations support the marginal domination of electron concentration over hole concentration. The experimental observation of nonlinear Hall resistivity with negative slope indicates that electrons are dominating. It is plausible that the finding of low MR is the result of the size of electron pockets is slightly larger than that of hole pockets. Five different types of nodal lines having $\ensuremath{\pi}$-Berry phase without spin orbit coupling (SOC) are presented as revealed from the DFT calculations: one infinite endless, one diamond-shaped, two with sixfold rotational symmetry, and one with threefold rotational symmetry. All nodal lines stack perpendicular to the crystallographic $c$ axis, with the exception of the diamond-shaped nodal line. The DFT calculations also manifest the two nodal lines which are still protected in the presence of SOC.