论文标题
拓扑材料候选者的低温热膨胀$β$ -PTBI $ _2 $和$β$ -bi $ _2 $ _2 $ PD
Low-temperature thermal expansion of the topological material candidates $β$-PtBi$_2$ and $β$-Bi$_2$Pd
论文作者
论文摘要
我们报告了基于二抗性的拓扑半学$β$ -PTBI $ _2 $和拓扑超导体$β$β$ -BI $ _2 $ _2 $ PD候选者的低温（$ t <$ 120 K）的热膨胀。四方$β$ -bi $ _2 $ pd的线性热扩散系数显示$ a $ a $ - 和$ c $轴之间的明显各向异性，而量的热量expant expansion expran-expansion $α_v$（$β$ -bi-bi $ _2 $ _2 $ _2 $ _2 $ _2 $ a $ a $ aus $ a $ a $ - 系数$α_v$（$β$ -ptbi $ _2 $）几乎与实验特定的热量相匹配，从中获得debye温度$θ_d= $ 199 k。另一方面，$α_v$（$β$ -bi $ _2 $ pd）合理地适合Debye模型，$θ_d= $ 138 K，从低温特定的热量中提取。对于两种化合物，获得了几乎恒定的grüneisen参数$γ\ $ 2。在最高$μ_0h = $ 16 t的两种化合物中均未观察到磁截图。我们将结果与其他基于BI的拓扑材料进行了比较。
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.
