Hysteretic electronic phase transitions in correlated charge density wave state of 1T-TaS2

The layered transition metal dichalcogenide 1T -TaS2 has evoked great interest owing to its particularly rich electronic phase diagram including different charge density wave (CDW) phases. However, few studies have focused on its hysteretic electronic phase transitions based on the in-depth discussion of the delicate interplay among temperature-dependent electronic interactions. Here, we report a sequence of spatial electronic phase transitions in the hysteresis temperature range (160-230 K) of 1T-TaS2 via variable-temperature scanning tunneling microscopy. Several emergent electronic states are investigated at multiscale during the commensurate CDW-triclinic CDW (CCDW-TCDW) phase transitions: a spotty-CDW state above similar to 160 K, a network-CDW (NCDW) state above similar to 180 K during the warmup process, a belt-TCDW state below similar to 230 K, a NCDW state below similar to 200 K, and finally a mosaic-CDW state below similar to 160 K during cooldown from the TCDW phase. These emergent electronic states are associated with the delicate temperature-dependent competition and/or cooperation of stacking-dependent interlayer interactions, intralayer electron-electron correlations, and electron-phonon (e-ph) coupling of 1T-TaS2. Our results not only provide insight to understand the hysteretic electronic phase transitions in the correlated CDW state, but also pave a way to realize more exotic quantum states by accurately and effectively tuning various interior interactions in correlated materials.

Automated summary

This study reports a sequence of spatial electronic phase transitions in 1T-TaS2 within the temperature range of 160-230 K, revealing several emergent electronic states during the CCDW-TCDW phase transitions. The competition and cooperation among stacking-dependent interlayer interactions, intralayer electron-electron correlations, and electron-phonon coupling are found to play important roles in these phase transitions, providing insights into understanding the hysteretic electronic phase transitions in correlated CDW state and exploring exotic quantum states in correlated materials.