Low-temperature thermal expansion of the topological material candidates 𝛽-PtBi2 and 𝛽-PdBi2

FRANCO D; HABERKORN N; PEDRAZZINI P; RUBRECHT B; CORREA VF; ROSA AJ

PHYSICA B - CONDENSED MATTER

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2022 vol. 641 p. 414102 - 414106

0921-4526

We report on the low-temperature (T < 120 K) thermal expansion of the bismuth-based topological semimetal β-PtBi2 and topological superconductor β-Bi2Pd candidates. The linear thermal-expansion coefficient of tetragonal β-Bi2Pd shows a pronounced anisotropy between the a- and c-axis while the volume thermal-expansion coefficient αV (β-Bi2Pd) is considerable larger than αV (β-PtBi2). The coefficient αV (β-PtBi2) nearly matches the experimental specific heat, from which a Debye temperature θD = 199 K is obtained. On the other hand, αV (β-Bi2Pd) reasonably fits the Debye model with θD = 138 K, extracted from the low-temperature specific heat. An almost constant Gr¨uneisen parameter Γ ≈ 2 is obtained for both compounds. No magnetostriction is observed in any of both compounds up to µ0H = 16 T. We compare our results with other Bi-based topological materials.