Pressure-Induced Two-Phase Superconductivity in the Rare-Earth Tritelluride LaTe₃

In the rare-earth tritelluride series (RTe₃), light members (R = La-Sm) host a unidirectional charge-density-wave (CDW) order, whereas heavy members (R = Tb-Tm) develop both unidirectional and bidirectional CDW orders. Upon chemical doping, both subsets exhibit superconductivity concomitant with suppression of the CDW order(s). In contrast, although pressure-induced superconductivity has been widely reported in the heavy members, its existence in the light members has remained unclear. Here, we establish a comprehensive pressure–temperature phase diagram of the lightest member, LaTe₃, using electrical transport, synchrotron x-ray diffraction, and Raman spectroscopy in diamond anvil cells up to 55.8 GPa, revealing two distinct superconducting phases. The first emerges as the CDW is strongly suppressed and rapidly reaches an optimal T_C~1.5 K near the CDW collapse at ~11 GPa, followed by only a weak decrease of T_C over the broad pressure range of 11-36 GPa. The second appears above ~31 GPa in conjunction with a Cmcm-to-Pmmm structural transition, marked by an abrupt increase of T_C from ~1.4 to ~2.5 K that then increases gradually up to 52.1 GPa.