Kondo-Peierls transition with nonsymmorphic zone boundary gap formation

TL;DR

This paper explores how nonsymmorphic symmetries in correlated electron systems can lead to uniform Peierls transitions and gap formations, exemplified by the hidden electric order in CeCoSi, through symmetry-breaking mechanisms.

Contribution

It reveals a novel mechanism for Peierls gap formation driven by nonsymmorphic symmetry breaking, linking it to Kondo singlet formations and hidden orders.

Findings

Nonsymmorphic symmetry breakings lift degeneracies at zone boundaries.

Uniform Peierls transition can occur with symmetry breaking.

Kondo singlet formation explains hidden electric order in CeCoSi.

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.