Charge density-waves with non-trivial orbital textures in rare earth tritellurides

TL;DR

This paper develops a theoretical framework for unconventional charge density waves in rare-earth tritellurides, revealing complex orbital textures and symmetry-breaking phenomena that align with recent experimental observations.

Contribution

It introduces a multi-orbital Ginzburg-Landau theory capturing non-trivial orbital order and symmetry-breaking in CDWs of rare-earth tritellurides, advancing understanding of their unconventional collective modes.

Findings

Unconventional CDWs with coexisting orbital order parameters

Orbital textures that break additional lattice symmetries

Identification of two competing phases with different symmetry properties

Abstract

Motivated by recent experiments reporting unconventional collective modes in the charge density-wave (CDW) state of rare-earth tritellurides $R$Te$_3$, we derive from a multi-orbital microscopic model on the square net a CDW Ginzburg-Landau theory that allows for non-trivial orbital order. Our analysis reveals unconventional CDWs where order parameters with distinct orbital character coexist due to an approximate symmetry of the low-energy model, which becomes exact in the limit of nearest-neighbor-only hopping and decoupled $p_x$, $p_y$ orbitals. Because of this coexistence, the resulting CDW pattern displays an orbital texture that generally breaks additional symmetries of the lattice besides those explicitly broken by the CDW wave-vector. In particular, we find two competing phases that differ in whether they break or preserve inversion and vertical mirror symmetries. We explain the mechanisms that favor each outcome, and discuss experimental probes that can distinguish the different phases.