Keywords :
Charge-density-wave instabilities; Charge-density-waves; Electron hole; Hole-instability; Isoelectronics; Isostructural; Octahedral layers; One-dimensional systems; Three-dimensional solids; Wave vector; Electronic, Optical and Magnetic Materials; Condensed Matter Physics
Abstract :
[en] The origin of the charge density wave (CDW) instabilities in the isostructural but not isoelectronic octahedral layers of the three-dimensional solids γ-Mo4O11 and P4W12O44 is discussed on the basis of first-principles density functional theory calculations. These layers contain three different and superposed one-dimensional (1D) systems (two diagonal and one horizontal) associated with the three t2g orbitals of the transition metal in octahedral coordination. Because of the special topology of the layers the three 1D systems are practically independent (hidden nesting) and the Lindhard function contains three different lines of intensity maxima associated with each of them. Clear cusps (six for P4W12O44 and four for γ-Mo4O11) occur at the intersections of these intensity lines. The wave vector of the structural modulations associated with some of these cusps from our calculations is in good agreement with the observed CDW wave vectors. The nature of the different modulations is analyzed on the basis of the calculated thermal dependence of intrachain and interchain coherence lengths of the diffuse lines associated with the diagonal and horizontal chains. Modulation in the diagonal chains is found to be more favorable than in the horizontal chain. The same type of wave vector is selected for γ-Mo4O11 and P4W12O44 despite having a different band filling. The coupling of the electronic instability to the phonon spectra and the relationship between the nature of the high-temperature modulation with the width of the octahedral layers is discussed. Among the two Magnéli phases the interlayer coupling is found to be somewhat stronger in η-Mo4O11. The relationship with other hidden-nesting series of materials as the rare-earth tellurides is commented.
Funding text :
This paper owes much to numerous structural studies on 2D oxides and bronzes by P. Foury-Leylekian (Orsay) to whom we are very indebted. The authors also thank A. Minelli (Oak Ridge) for useful discussions concerning her IXS studies on the and E. Duverger-N\u00E9dellec (Bordeaux) for sharing the results of her structural studies. B.G. acknowledges computational resources provided by the Consortium des \u00C9quipements de Calcul Intensif (C\u00C9CI), funded by the Fonds de la Recherche Scientifique (F.R.S.-FNRS) under Grant No. 2.5020.11 and the Tier-1 Lucia supercomputer of the Walloon Region, infrastructure funded by the Walloon Region under the Grant Agreement No. 1910247. B.G., M.P., and P.O. acknowledge support from Grant No. PID2022-139776NB-C62 funded by the Spanish MCIN/AEI/10.13039/501100011033 and by the ERDF, a way of making Europe and the Severo Ochoa program from Spanish MINECO (Grant No. CEX2021-001214-S). E.C. was supported by Grant No. PID2022-139776NB-C61 funded by the Spanish MCIN/AEI/10.13039/501100011033 and AEI through the Severo Ochoa MaTrans42 (Grant No. CEX2023-0001263-S) Excellence Centre distinction. B.G., M.P., P.O., and E.C. acknowledge support from Generalitat de Catalunya (CERCA program and Grant No. 2021SGR01519).
Scopus citations®
without self-citations
0
