Angle-resolved photoemission study of the evolution of band structure and charge density wave properties inRTe3(R=Y, La, Ce, Sm, Gd, Tb, and Dy

Abstract

We present a detailed ARPES investigation of the RTe 3 family, which sets this system as an ideal "textbook" example for the formation of a nesting driven Charge Density Wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDW instabilities, from the opening of large gaps on the best nested parts of Fermi Surface (FS) (up to 0.4eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k-space. An additional advantage of RTe 3 is that the band structure can be very accurately described by a simple 2D tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure, by comparing our ARPES measurements with Linear Muffin-Tin Orbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and, for the first time, of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k-space, the evolution of the CDW wave vector with R and the shape of the residual metallic pockets. Finally, we give an estimation of the CDW interaction parameters and find that the change in the electronic density of states n(E f ), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.

Alternative route to charge density wave formation in multiband systems

“…The inclusion of a small but nonzero hopping term between p x and p z (V xz ≠ 0) lifts the degeneracy at the intersection points of the two quasi-1D Fermi surfaces, which is emphasized in Fig. 1D, and improves the agreement with the experimental Fermi surface, although Q* remains the best nesting vector (12). Therefore, mechanisms beyond purely electronic ones have been conjectured to play an important role in selecting the ordering vector and forming the density wave.…”

“…Among them, the prototypical ErTe 3 (Materials and Methods) undergoes a first CDW transition at T CDW1 = 265 K followed by a second one at T CDW2 = 155 K, and it allows a robust access to its intrinsic CDW properties. The ordering vectors Q 1 and Q 2 are parallel to but incommensurate with the reciprocal lattice vectors c* jj c and a* jj a, respectively (11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The electronic properties of these layered CDW compounds can be modeled by considering a single Te plane (Fig.…”

Wave-vector-dependent electron-phonon coupling and the charge-density-wave transition inTbTe3

“…The rare-earth-tritellurides ReTe 3 (Re = La, Ce, Gd, Tb, …) are prime examples of CDW ordered ground states. Angleresolved photoemission spectroscopy (ARPES) measurements [6] [7] of several rare-earth tritelluride compounds including TbTe 3 lead to the assumption of a nesting driven CDW order and, hence, ReTe 3 are often used as canonical Peierls-like CDW systems. On the other hand, theoretical investigations in rare-earth tritellurides [4] revealed a nesting feature, i.e.…”

Probing the Fermi surface by positron annihilation and Compton scattering

“…44 Moreover, angle-resolved photoemission is unable to see the parts of the Fermi surface gapped by the CDW. 45,46 In Fig. 5, the calculated Fermi surface of LuTe 3 is shown, along with a nesting vector which matches the experimentally observed incommensurate order.…”