LaTe3

LaTe3
Name	LaTe3
Caption	Layered rare-earth tritelluride crystal structure
Formula	LaTe3
Crystal system	Orthorhombic (pseudo-tetragonal)
Space group	Cmcm (approx.)
Color	Silver-gray
Mol weight	363.63 g/mol

LaTe3 is a layered rare-earth tritelluride compound composed of lanthanum and tellurium that belongs to the family of rare-earth chalcogenides. It is notable for exhibiting an incommensurate charge density wave phase at ambient conditions and for serving as a platform to study low-dimensional electronic instabilities and electron–phonon coupling. The material has been the subject of angle-resolved photoemission, x‑ray diffraction, transport, and theoretical studies alongside related compounds such as the rare-earth series RTe3 and other low-dimensional materials.

Introduction

LaTe3 crystallizes in a layered structure in which double Te sheets alternate with La–Te slabs, producing structural anisotropy similar to the transition metal dichalcogenides MoS2, TiSe2, and the high-temperature superconductor precursor La2CuO4. The rare-earth tritellurides connect to broader themes in condensed matter research including Fermi surface nesting studies exemplified by work on NbSe3, TaS2, and the Bechgaard salts such as (TMTSF)2PF6. Interest in LaTe3 stems from its accessible charge density wave transition, tunability across the rare-earth series related to chemical pressure in comparisons with CeTe3, NdTe3, and SmTe3, and its role in benchmarking first-principles methods like those used in studies of Graphene and Sr2RuO4.

Crystal Structure and Synthesis

The crystal structure of LaTe3 is built from planar tellurium sheets interleaved with lanthanum-containing slabs, producing quasi-two-dimensional bonding similar to that in Bi2Sr2CaCu2O8 and Ca2RuO4. Structural determinations use single-crystal x‑ray diffraction protocols akin to methods applied to YBa2Cu3O7 and K2NiF4 families. Synthesis is typically achieved by self-flux growth or chemical vapor transport methods paralleling techniques used for FeSe and VSe2, enabling millimeter-scale single crystals for measurements. Comparisons across the rare-earth series (e.g., GdTe3, TbTe3) reveal lattice-parameter trends consistent with lanthanide contraction documented in studies of CeO2 and LaMnO3.

Electronic Properties and Fermi Surface

Band structure and Fermiology of LaTe3 show quasi-two-dimensional sheets derived predominantly from Te 5p orbitals, analogous to the Te-derived bands in BiTeI and the p-derived Fermi surfaces in PbTe. Angle-resolved photoemission spectroscopy (ARPES) mapping, borrowing methodologies used for CuO2 planes and Bi2Se3, reveals nested parallel Fermi surface sections that are implicated in the charge density wave formation, in the manner of nesting-driven models applied to TaSe2 and K0.3MoO3. Density functional theory (DFT) calculations using protocols akin to those for FeAs pnictides and MgB2 reproduce the gross Fermi surface topology and quantify nesting vectors comparable to those extracted for NbSe2 and ErTe3. Electronic anisotropy shows parallels with layered superconductors like Bi2212 and low-dimensional conductors such as Sr2RuO4.

Charge Density Wave Order

LaTe3 exhibits an incommensurate unidirectional charge density wave (CDW) at temperatures comparable to CDW transitions in NbSe3 and TaS2, characterized by a modulation vector that partially gaps the nested portions of the Fermi surface. X‑ray and electron diffraction studies follow techniques used to detect CDW order in 1T-TaS2 and K0.3MoO3, revealing satellite reflections and domain structures reminiscent of stripe phases discussed in the context of La2-xSrxCuO4 and charge order in YBa2Cu3O6+x. Temperature- and pressure-dependent studies compare to pressure tuning in TiSe2 and chemical substitution effects observed in BaFe2As2 derivatives. The interplay of CDW amplitude, phase fluctuations, and residual metallic pockets invites comparisons with the pseudogap phenomenology of Bi2Sr2CaCu2O8 and collective mode dynamics investigated in Kohn anomaly studies.

Transport and Optical Properties

Transport measurements in LaTe3 show anisotropic resistivity and metallic behavior above the CDW transition, paralleling observations in TaSe2 and organic conductors like (BEDT-TTF)2X. Magnetoresistance and Hall effect studies use analysis approaches developed for Graphene and LaNiO3 to extract carrier density and mobility influenced by partial Fermi surface gapping similar to effects seen in Cr and 2H-NbSe2. Optical conductivity and infrared spectroscopy identify a partial gap and collective mode responses using experimental protocols comparable to optical studies on SrTiO3 and YBa2Cu3O7, with spectral weight transfer reflecting the CDW-induced reconstruction akin to observations in 1T-TiSe2.

Experimental Methods

Characterization of LaTe3 employs ARPES, single-crystal and powder x‑ray diffraction, transmission electron microscopy, Raman scattering, scanning tunneling microscopy (STM), and transport probes, leveraging instrumentation and analysis pipelines analogous to those used for Bi2Se3, NbSe2, and FeSe investigations. High-resolution synchrotron x‑ray diffraction and resonant elastic x‑ray scattering follow methodologies applied to La2CuO4 and SmB6 to detect superlattice peaks and CDW domains. Low-temperature magnetotransport and quantum oscillation experiments adopt techniques refined on systems such as CeCoIn5 and Sr2RuO4 to map Fermi surface pockets surviving the CDW.

Theoretical Modeling and Calculations

Theoretical efforts combine first-principles DFT, tight-binding modeling, and many-body approaches including random phase approximation and electron–phonon coupling calculations, using formalisms applied to MgB2, TaSe2, and Graphene. Model Hamiltonians capture nesting instabilities similar to theoretical treatments of Kohn anomaly systems and employ numerical methods paralleling work on spin- and charge-order in Hubbard model studies of CuO2-based materials. Calculations address phonon softening, electronic susceptibility, and the role of dimensionality, drawing conceptual links to superconductivity and density-wave competition investigated in TiSe2 and BaFe2As2.

Category:Rare earth compounds Category:Chalcogenides