The Interplay of Weyl electronic structure with long-range magnetic structure in Co_xFe_1-x Ge compounds

The interplay between magnetism and topology plays a revolutionary role in material research, providing an additional means to control the symmetries exhibited by materials and opening the possibility for the next-generation electronic devices. In this work, we study alloys of the B20 Chiral crystals Co_xFe_1-xGe for x=0.1, 0.2, via density functional theory by investigating the electronic structure and topological properties by symmetry analysis of the multiplicity of the bands and their degeneracy. Our results reveal that magnetization increases smoothly from nonmagnetic CoGe to ferromagnetic Co_xFe_1-xGe when x=0.1,0.2. The effect of Spin-orbit coupling (SOC) is systematically varied simultaneously with the magnetic structure to investigate the topological Weyl crossing points. Long Fermi arcs are observed connecting their surface projections that confirm the Weyl fermionic behavior consistent with other work. Variation in magnetic structure and SOC determine the shape, size, and seemingly the chirality of Fermi arcs. We also develop a simple tight-binding model to confirm Weyl points (WP) calculations for our system. Thus, our results reveal that Co_xFe_1-xGe Weyl semimetals are excellent materials to experimentally explore quantum topological phases by tuning unconventional chiral fermions.