Detecting Multiple Symmetry Breaking and Unconventional CDW Order via the Higgs Mode

In the quantum materials, the comprehension of quantum order such as superconductivity and charge density waves, its related collective excitations, and their significance stands as a pivotal challenge in the context of spontaneously broken symmetries. The recent discovery of the axial nature of collective excitations (Higgs mode) in Rare-earth tritelluridesRTe3, a quasi-two-dimensional square-net materials, suggested an unconventional charge density waves (CDW). Despite the detection of the axial Higgs mode, the underlying microscopic origin of its axial nature still remains elusive. Here, we carried out a careful experiment on RTe3 to probe the underlying microscopic origin of the axial Higgs mode. Our investigation unveils the simultaneous breaking of multiple symmetries (translation and mirrors) with the emergence of high temperature (primary) CDW phase, however, the low temperature CDW (secondary) phase appear to exclusively breaks the translation symmetry. Intriguingly, we note that the amplitude mode associated with the primary CDW exhibit axial nature, whereas the amplitude mode corresponding to secondary CDW show conventional nature. Our finding provides unambiguous evidence of the Axial Higgs mode from simultaneously breaking of multiple symmetries and open the possibility for the detection of unconventional change order in these materials.