Time-domain identification of distinct mechanisms for competing charge density waves in a rare-earth tritelluride

Yifan Su, B. Q. Lv, Alfred Zong, Aaron Müller, Sambuddha Chattopadhyay, Pavel E. Dolgirev, Anisha G. Singh, Joshua A. W. Straquadine, Dongsung Choi, Doron Azoury, Masataka Mogi, Ian R. Fisher, Eugene Demler & Nuh Gedik

DOI: https://doi.org/10.1038/s41567-026–03382‑5 

Abstract:

Understanding the origin of phase transitions and the interactions between distinct phases remains a central task in condensed-matter physics. Charge-density-wave (CDW) systems provide a useful setting to investigate these questions. Although the dominant CDW phases in many materials can be explained through electron–phonon interactions, certain CDW phase transitions remain poorly understood, challenging conventional paradigms. One example is the rare-earth tritelluride ErTe₃, which hosts two competing CDW orders. Although electron–phonon coupling accounts for the dominant order, the mechanism behind the subdominant order remains unclear. In this study, we combine time- and angle-resolved photoemission spectroscopy and time-dependent Ginzburg–Landau theory to establish a time-domain approach for probing phase transitions in solid-state systems. By analysing the distinct recovery dynamics of the two CDW orders in ErTe₃ following light excitation, we reveal a novel nucleation and growth mechanism that probably drives the secondary CDW phase transition. More broadly, this work provides a time-domain framework for studying phase transitions and phase competition in quantum materials.