Distinct charge density wave instabilities in PrTen (n=2, 3) and ErTe3 investigated via ARPES and XAS

Abstract

Understanding the origin of distinct charge density wave (CDW) instabilities in layered RTen (n=2, 3) compounds (R, rare earth element) has been an important issue. In this research update, we have investigated the electronic structures of PrTen (n=2, 3) and ErTe3 layered CDW compounds employing angle-resolved photoemission spectroscopy (ARPES) and soft x-ray absorption spectroscopy (XAS). The trivalent valency of R3+ ions is confirmed for PrTen (n=2, 3) and ErTe3, supporting that R-Te slabs serve as charge reservoirs and that the CDW instability occurs in the partially filled Te sheets. Both R4d→4f resonant photoemission spectroscopy and photon-energy map measurements provide evidence that R4f electrons do not contribute directly to the CDW formation but that the indirect contribution from Pr 4f electrons through the Pr 4f-Te 5p hybridization is feasible in PrTen (n=2, 3). Circular and linear dichroism ARPES measurements indicate that the chirality of the Te 5p orbitals certainly plays a role in the CDW formation of RTe3 (R=Pr, Er) while it is relatively weak in PrTe2, and that the EF-crossing orbitals, responsible for the CDW formation, are ordered in plane (in the ac plane) in all of them. Different CDW-induced Fermi surface reconstructions between RTe3 and RTe2 are due to (i) the existence of two Te sheets and one Te sheet per unit cell in RTe3 and RTe2, respectively, so as to produce different numbers of hole carriers, and (ii) the different lattice parameters of Te sheets in RTen, leading to the different densities of states at EF. © 2024 American Physical Society.