CaFeAsF量子振荡的拓扑频移
Topological frequency shift of quantum oscillation in CaFeAsF
摘要：
Guo，Alexandradinata，\textit{et al.}最近提出，由于线性带色散所特有的有效质量的能量依赖性，Dirac/Weyl费米子的量子振荡频率呈现与$T^2$成比例的负移。我们在$T$ = 9 K的温度下测量了CaFeAsF的Shubnikov-de Haas振荡。随着$T$的增加，$α$狄拉克电子的频率呈现负移，而$β$薛定谔空穴的频率则没有。对于$T \geqslant 5$ K，其中$β$可忽略，$α$ -频移与$T^2$成比例，并且其速率在实验精度内与理论预测一致。在较低的温度下，$α$和$β$的位移偏离理论预期，我们将其归因于由于频率之间的不利干扰而导致的频率确定的不准确性。我们的研究结果证实，拓扑频移可以用来识别狄拉克/外尔费米子时，量子振荡频率可以准确地确定。
英文摘要：
Guo, Alexandradinata, \textit{et al.} have recently proposed that quantum-oscillation frequencies from Dirac/Weyl fermions exhibit a negative shift proportional to $T^2$ because of the energy dependence of the effective mass peculiar to a linear band-dispersion. We have measured Shubnikov--de Haas oscillation in CaFeAsF up to $T$ = 9 K. The frequency of the $α$ Dirac electron exhibits a negative shift with increasing $T$, while that of the $β$ Schrödinger hole does not. For $T \geqslant 5$ K where $β$ is negligible, the $α$-frequency shift is proportional to $T^2$ and its rate agrees with the theoretical prediction within experimental accuracy. At lower temperatures, the shifts of $α$ and $β$ deviate from theoretical expectations, which we ascribe to the inaccuracy in the frequency determination due to unfavorable interference between frequencies. Our results confirm that the topological frequency shift can be utilized to identify Dirac/Weyl fermions when quantum-oscillation frequencies can be determined accurately.
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