Low-temperature thermal expansion of the topological material candidates $β$-PtBi$_2$ and $β$-Bi$_2$Pd

V. F. Correa; P. Pedrazzini; D. G. Franco; A. J. Rosa; B. Rubrecht; N. Haberkorn

doi:10.1016/j.physb.2022.414102

paper

Low-temperature thermal expansion of the topological material candidates $β$ -PtBi $_{2}$ and $β$ -Bi $_{2}$ Pd

arXiv:2204.02327 · doi:10.1016/j.physb.2022.414102

Abstract

We report on the low-temperature ( $T <$ 120 K) thermal expansion of the bismuth-based topological semimetal $β$ -PtBi $_{2}$ and topological superconductor $β$ -Bi $_{2}$ Pd candidates. The linear thermal-expansion coefficient of tetragonal $β$ -Bi $_{2}$ Pd shows a pronounced anisotropy between the $a$ - and $c$ -axis while the volume thermal-expansion coefficient $α_{V}$ ( $β$ -Bi $_{2}$ Pd) is considerable larger than $α_{V}$ ( $β$ -PtBi $_{2}$ ). The coefficient $α_{V}$ ( $β$ -PtBi $_{2}$ ) nearly matches the experimental specific heat, from which a Debye temperature $θ_{D} =$ 199 K is obtained. On the other hand, $α_{V}$ ( $β$ -Bi $_{2}$ Pd) reasonably fits the Debye model with $θ_{D} =$ 138 K, extracted from the low-temperature specific heat. An almost constant Grüneisen parameter $Γ \approx$ 2 is obtained for both compounds. No magnetostriction is observed in any of both compounds up to $μ_{0} H =$ 16 T. We compare our results with other Bi-based topological materials.

arXiv comment7 pages, 3 figures

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Enhanced weak superconductivity in trigonal $γ$ -PtBi $_{2}$

Low-temperature thermal expansion of the topological material candidates β-PtBi2​ and β-Bi2​Pd

Abstract

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Low-temperature thermal expansion of the topological material candidates $β$ -PtBi $_{2}$ and $β$ -Bi $_{2}$ Pd