Observation of Optical and Electrical In-Plane Anisotropy in High-Mobility Few-Layer ZrTe5,Nano Letters

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Observation of Optical and Electrical In-Plane Anisotropy in High-Mobility Few-Layer ZrTe5
Nano Letters ( IF 9.6 ) Pub Date : 2016-11-29 00:00:00 , DOI: 10.1021/acs.nanolett.6b02629
Gang Qiu ₁ , Yuchen Du ₁ , Adam Charnas ₁ , Hong Zhou ₁ , Shengyu Jin ₁ , Zhe Luo ₁ , Dmitry Y. Zemlyanov ₁ , Xianfan Xu ₁ , Gary J. Cheng ₁ , Peide D. Ye ₁

Affiliation

Transition metal pentatelluride ZrTe₅ is a versatile material in condensed-matter physics and has been intensively studied since the 1980s. The most fascinating feature of ZrTe₅ is that it is a 3D Dirac semimetal which has linear energy dispersion in all three dimensions in momentum space. Structure-wise, ZrTe₅ is a layered material held together by weak interlayer van der Waals force. The combination of its unique band structure and 2D atomic structure provides a fertile ground for more potential exotic physical phenomena in ZrTe₅ related to 3D Dirac semimentals. However, the physical properties of its few-layer form have yet to be thoroughly explored. Here we report strong optical and electrical in-plane anisotropy of mechanically exfoliated few-layer ZrTe₅. Raman spectroscopy shows a significant intensity change with sample orientations, and the behavior of angle-resolved phonon modes at the Γ point is explained by theoretical calculations. DC conductance measurement indicates a 50% of difference along different in-plane directions. The diminishing of resistivity anomaly in few-layer samples indicates the evolution of band structure with a reduced thickness. A low-temperature Hall experiment sheds light on more intrinsic anisotropic electrical transport, with a hole mobility of 3000 and 1500 cm²/V·s along the a-axis and c-axis, respectively. Pronounced quantum oscillations in magnetoresistance are observed at low temperatures with the highest electron mobility up to 44 000 cm²/V·s.

中文翻译：

高迁移率几层ZrTe ₅的光电平面各向异性

过渡金属五碲化物ZrTe ₅是凝聚态物理中的一种通用材料，自1980年代以来就进行了深入研究。ZrTe ₅最引人入胜的特征是它是一种3D Dirac半金属，在动量空间的所有三个维度上都具有线性能量散布。在结构上，ZrTe ₅是通过弱的层间范德华力保持在一起的层状材料。其独特的能带结构和2D原子结构的结合为ZrTe _5中更多潜在的奇异物理现象提供了沃土与3D Dirac半要素有关。然而，其几层形式的物理性质尚未被彻底探究。在这里，我们报告了机械剥落的多层ZrTe _5的强光学和电平面内各向异性。拉曼光谱显示样品强度随样品方向发生显着变化，并且通过理论计算解释了Γ点处的角度分辨声子模式的行为。直流电导测量表明沿不同平面方向的差异为50％。几层样品中电阻率异常的减小表明厚度减小的带结构的演变。低温霍尔实验揭示了更固有的各向异性电传输，空穴迁移率分别为3000和1500 cm ²/ V·s分别沿a轴和c轴。在低温下观察到明显的磁阻量子振荡，其最高电子迁移率高达44 000 cm ² / V·s。

更新日期：2016-11-29

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