Pressure-Induced Superconductivity in the Charge-Density-Wave Compound LaTe2–x Sb x (x = 0 and 0.4)

Abstract

Magnetic CeTe2 achieving superconductivity under external pressure has received considerable attention. The intermingling of 4f and 5d electrons from Ce raised the speculation of an unconventional pairing mechanism arising from magnetic fluctuations. Here, we address this speculation using a nonmagnetic 4f-electron-free LaTe2 as an example. No structural phase transition can be observed up to 35 GPa in the in situ synchrotron diffraction patterns. Subsequent high-pressure electrical measurements show that LaTe2 exhibits superconductivity at 20 Gpa with its T c (4.5 K) being two times higher than its Ce-counterpart. Detailed theoretical calculations reveal that charge transfer from the 4p orbitals of the planar square Te–Te network to the 5d orbitals of La is responsible for the emergence of superconductivity in LaTe2, as confirmed by Hall experiments. Furthermore, we study the modulation of q CDW by Sb substitution and find a record high T c onset ∼ 6.5 K in LaTe1.6Sb0.4. Our work provides an informative clue to comprehend the role of 5d–4p hybridization in the relationship between charge density wave (CDW) and superconductivity in these RETe2 (RE = rare-earth elements) compounds.