论文标题
依赖角度的磁势及其对W2AS3中LIFSHITZ过渡的影响
Angle-dependent magnetoresistance and its implications for Lifshitz transition in W2As3
论文作者
论文摘要
Lifshitz转变代表了费米表面结构的突然重建，从而导致材料电子性质的异常。这样的过渡不一定依赖于对称性的破坏，因此是拓扑结构的。它具有了解许多异国情调量子现象的起源的关键，例如拓扑迪拉克/Weyl半含量中极大的磁化（MR）机制。在这里，我们报告了W2AS3单晶的角度依赖性MR（ADR）和热电效应的研究。该化合物显示了大型不饱和MR（在4.2 K和53 T时约为70000％）。最引人注目的发现是，ADR从高于40 K的水平哑铃状形状到30 K以下的垂直莲花状模式显着变形。30-40K的垂直莲花样图案也对应于Hall效应，热电器和Nernst系数的实质性变化，这意味着Fermi表面拓扑的突然变化。这种温度引起的Lifshitz过渡会导致电子孔传输的补偿和大型MR。因此，我们建议在无法进行直接的费米地面测量时，可以适用于检测各种量子状态的费米地面变化。
Lifshitz transition represents a sudden reconstruction of Fermi surface structure, giving rise to anomalies in electronic properties of materials. Such a transition does not necessarily rely on symmetry-breaking and thus is topological. It holds a key to understand the origin of many exotic quantum phenomena, for example the mechanism of extremely large magnetoresistance (MR) in topological Dirac/Weyl semimetals. Here, we report studies of the angle-dependent MR (ADMR) and the thermoelectric effect in W2As3 single crystal. The compound shows a large unsaturated MR (of about 70000% at 4.2 K and 53 T). The most striking finding is that the ADMR significantly deforms from the horizontal dumbbell-like shape above 40 K to the vertical lotus-like pattern below 30 K. The window of 30-40 K also corresponds substantial changes in Hall effect, thermopower and Nernst coefficient, implying an abrupt change of Fermi surface topology. Such a temperature-induced Lifshitz transition results in a compensation of electron-hole transport and the large MR as well. We thus suggest that the similar method can be applicable in detecting a Fermi-surface change of a variety of quantum states when a direct Fermi-surface measurement is not possible.
