Angle-resolved and resonant photoemission spectroscopy study of the Fermi surface reconstruction in the charge density wave systemsCeTe2andPrTe2

Abstract

The electronic structures of a charge density wave (CDW) system RTe 2 (R = Ce, Pr) have been investigated by employing angle-resolved photoemission spectroscopy (ARPES) and the first-principles band structure method. The R 4f hybridization peak (4f n c m−1 ) in the R 4f PES spectrum is located deeper in PrTe 2 than in CeTe 2 and R 4f spectral intensity near E F is much weaker in PrTe 2 than in CeTe 2 , implying the importance of the hybridization between Ce 4f and Te(1) 5p electrons. For both CeTe 2 and PrTe 2 , the metallic states crossing the Fermi level (E F ) are observed below the CDW transition temperature, indicating the existence of the partially ungapped Fermi surfaces (FSs). The zigzag features having the fourfold rotational symmetry are observed near the X point in the FS of CeTe 2 , but not in the FS of PrTe 2 . The tight-binding model calculations show that the zigzag FS features in CeTe 2 can be described as the CDW-induced FS reconstruction due to the 4 × 4 CDW supercell structure. The effect of the linear dichroism is observed in ARPES, suggesting that the E F -crossing states have mainly the in-plane orbital character. The photon-energy maps for the near-E F states exhibit the straight vertical dispersions for both CeTe 2 and PrTe 2 , demonstrating the dominant two-dimensional character in RTe 2 (R = Ce, Pr).

The Role of Delocalized Chemical Bonding in Square-Net-Based Topological Semimetals

“…An electron count of seven should destabilize the square-net and indeed most data points, marked blue in Figure 5, are either solid solutions with electron counts slightly above 6.5 or lanthanide dichalcogenides such as LaTe 2 , which are known to exhibit charge density waves (CDWs). [39][40][41][42][43][44][45][46] Thus, those compounds, although listed as square-net materials in the ICSD, in reality crystallize most often in distorted structures. Recently, the evolution of these distortions in GdSb x Te 2−x−δ with respect to x was discussed in the context of TSM properties.…”

Charge Density Waves and Magnetism in Topological Semimetal Candidates GdSbxTe2−x−δ

“…In previous studies, single crystals of rare earth ditellurides ( Ln Te 2 ) were synthesized by several different methods, including chemical vapor transport (CVT), self‐flux method, molten alkali–metal–halide flux method, mineralization from a nominally stoichiometry binary mixture of elements, and high‐temperature Bridgman method . For synthesis of the ternary compound with Sb, we adopted CVT using iodine as the transport agent, similar to the single crystal growth of CeSbTe reported in recent work .…”

“…As stated above, nonstoichiometric Ln Sb x Te 2− x − δ as well as stoichiometric Ln Te 2 can be structurally distorted, which has been related to charge density wave (CDW) formations . For an ideal 1D linear chain with a half filling, the lattice can undergo a Peierls distortion at the cost of elastic energy and form a CDW at low temperature.…”

“…Such a study is critical because Ln SbTe phases (with Ln = Lanthanide) are likely to undergo lattice distortions, especially when they are nonstoichiometric. One good example is the rare‐earth ditellurides ( Ln Te 2 ), whose structural distortions have been heavily studied. So far, GdSbTe has not been investigated for possible nonstoichiometry or structural instabilities.…”

The 7 × 1 Fermi Surface Reconstruction in a Two-dimensional f -electron Charge Density Wave System: PrTe3

“…The dichroic ARPES image plots for PrTe 3 reveal several features. (i) Very dispersive bands are observed in ARPES of PrTe 3 and the large-energy-scale band structures of PrTe 3 are very similar to those of R Te 2 ( R = Ce, Pr) 30 42 . (ii) The effects of both the LD and CD are observed clearly.…”