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 $R{\mathrm{Te}}_{2}$ $(R=\text{Ce},\text{Pr})$ have been investigated by employing angle-resolved photoemission spectroscopy (ARPES) and the first-principles band structure method. The $R$ $4f$ hybridization peak $(4{f}^{n}{c}^{m\ensuremath{-}1})$ in the $R$ $4f$ PES spectrum is located deeper in ${\mathrm{PrTe}}_{2}$ than in ${\mathrm{CeTe}}_{2}$ and $R$ $4f$ spectral intensity near ${E}_{F}$ is much weaker in ${\mathrm{PrTe}}_{2}$ than in ${\mathrm{CeTe}}_{2}$, implying the importance of the hybridization between Ce $4f$ and Te(1) $5p$ electrons. For both ${\mathrm{CeTe}}_{2}$ and ${\mathrm{PrTe}}_{2}$, 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 ${\mathrm{CeTe}}_{2}$, but not in the FS of ${\mathrm{PrTe}}_{2}$. The tight-binding model calculations show that the zigzag FS features in ${\mathrm{CeTe}}_{2}$ can be described as the CDW-induced FS reconstruction due to the $4\ifmmode\times\else\texttimes\fi{}4$ 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 ${\mathrm{CeTe}}_{2}$ and ${\mathrm{PrTe}}_{2}$, demonstrating the dominant two-dimensional character in $R{\mathrm{Te}}_{2}$ $(R=\text{Ce},\text{Pr})$.