Gapless topological Peierls-like instabilities in more than one dimension

Abstract

A periodic lattice distortion that reduces the translational symmetry folds electron bands into a reducedBrillouin zone, leading to band mixing and a tendency to gap formation, as in the Peierls transition in one-dimensional systems. However, in higher dimensions, the resulting phase can present topological obstructionspreventing a complete gap opening. We discuss two different mechanisms for such obstructions: emergentWeyl nodes and symmetry protected band crossings. Based on density-functional calculations, we show thesemechanisms are at play in trigonal PtBi2.