Fermi surface nesting and topological and magnetoresistance properties of ThX2 (X = As, Sb, Bi)

In this constantly expanding and evolving era of advanced technology, there is great demand for a compound that boasts a plethora of exotic properties. To procure such a compound, we conducted a thorough analysis of the lattice and electronic properties of several Th-based compounds using first -principle calculations. A Dirac -like crossing displaying nodal line characteristics has been observed in the phonon spectrum of ThAs2, exhibiting nontriviality that has been further confirmed by a nonzero value of the Berry phase. In the analysis of the electronic structure of all the compounds, we have detected nontrivial topological features that were manifested by means of gap plane and Z2 calculations. Moreover, a thorough examination of the compounds further revealed the presence of nodal surfaces, which have been analyzed for their intricate symmetry. The Fermi surface of ThAs2 has been scrutinized for nesting properties through the computation of the real and imaginary components of Lindhard susceptibility, which have shown peaks at the same wave vector, indicating the possibility of a charge density wave in this compound. Furthermore, the application of a 5 T magnetic field has revealed a giant negative magnetoresistance in ThAs2 at 10 K. The coexistence of topological fermions and bosons in the same compound is a rare phenomenon and, combined with the probable presence of charge density waves and negative magnetoresistance, this provides an in-depth, comprehensive understanding of its physical properties and also presents a promising platform for further experimental verifications.