Multiple charge-density waves in R₅Ir₄Si₁₀ (R = Ho, Er, Tm, and Lu)

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van Smaalen, Sander ; Shaz, Mohammad ; Palatinus, Lukas ; Daniels, Peter ; Galli, Federica ; Nieuwenhuys, Gerard J. ; Mydosh, J. A.:
Multiple charge-density waves in R₅Ir₄Si₁₀ (R = Ho, Er, Tm, and Lu).
In: Physical Review B. Bd. 69 (2004) Heft 1 . - No. 014103.
ISSN 0163-1829
DOI: https://doi.org/10.1103/PhysRevB.69.014103

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Abstract

he charge-density-wave (CDW) transitions in compounds R5Ir4Si10 (R=rare−earth element) have been studied by x-ray-diffraction and electrical conductivity experiments for temperatures between 20 and 300 K. At TCDW incommensurate CDW’s [q⃗ =(±0.25±δ)c* with δ≈0.03] develop in compounds with R=Ho, Er, Tm, and (Lu0.16Er0.84), while commensurate CDW’s [q⃗ =(n/7)c*] develop in compounds with R=Lu and (Lu0.34Er0.66). TCDW varies between 83 K in R=Lu and 161.4 K in R=Ho. The compounds with an incommensurate CDW exhibit a second transition at Tlock−in<TCDW, with Tlock−in between 55 K in R=Er and 111.5 K in R=Tm. In Ho5Ir4Si10 and Er5Ir4Si10 this is a pure lock-in transition at which δ becomes zero. In Tm5Ir4Si10 and (Lu0.16Er0.84)5Ir4Si10δ also becomes zero, but below Tlock−in additional satellite reflections have been discovered, at commensurate positions (n/8)c* in Tm5Ir4Si10 and at incommensurate positions (n/8±δ2)c* with δ2≈0.01 in (Lu0.16Er0.84)5Ir4Si10. The development of this second CDW can be understood by a two-step mechanism similar to the mechanism for the development of the primary CDW in Er5Ir4Si10 [Galli et al., Phys. Rev. Lett. 85, 158 (2000)]. At Tlock−in the primary CDW becomes commensurate, leading to a partly restoration of the Fermi surface, as evidenced by an anomalous decrease of the electrical resistivity for T below Tlock−in in Ho5Ir4Si10 and Er5Ir4Si10. The modified Fermi surface then provides the favorable nesting conditions for the development of a second CDW in Tm5Ir4Si10 and (Lu0.16Er0.84)5Ir4Si10. The electronic character of this transition is suggested by the anomalous increase of the resistivity for T below Tlock−in.