Kondo-Peierls transition with nonsymmorphic zone boundary gap formation

Abstract

We study nonsymmorphic space group symmetry breakings in correlated electron systems. Under nonsymmorphic symmetry, it is well known that there are degeneracies in the electronic Bloch states at the Brillouin zone boundaries. When the system undergoes a phase transition into an ordered phase with breaking the nonsymmorphic symmetry, the degeneracy is lifted. This happens even when the order parameter is uniform. We point out that this general feature leads to various {\it uniform} Peierls transition in nonsymmorphic systems. In particular, we show that such mechanism of the Peierls gap formation can be realized accompanying with uniform anisotropic Kondo singlet formations. This explains the hidden electric order observed in CeCoSi.