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arXiv · 1901.06061

Layered semiconductor EuTe 4 with charge density wave order in square tellurium sheets

D. Wu·Q. M. Liu·S. L. Chen·G. Y. Zhong·J. Su·L. Y. Shi·L. Tong·G. Xu·P. Gao·y·N. L. Wang
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Abstract

We report a novel quasi-two dimensional compound of EuTe4 hosting charge density waves (CDW) instability. The compound has a crystallographic structure in a orthorhombic space group Pmmn (No.59) with cell parameters a = 4.6347(2){\AA}, b = 4.5119(2){\AA}, c = 15.6747(10){\AA} at room temperature. The pristine structure contains consecutive near-square Te sheets separated by corrugated Eu-Te slabs. Upon cooling, the compound experiences a phase transition near 255 K. X-ray crystallographic analysis and transmission electron microscopy (TEM) measurements reveal strong structural distortions in the low temperature phase, showing a superstructure with a periodic formation of Te-trimers in the monolayer Te sheets, yielding evidence for the formation of CDW order. The charge transport properties show a semiconducting behavior in the CDW state. Density functional theory calculations reveals a Fermi surface nesting driven instability with a nesting vector in good agreement with the one observed experimentally. Our finding provides a promising system for the study of CDW driven 2D semiconducting mechanisms, which would shed a new light on exploring novel 2D semiconductors with collective electronic states.

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D. Wu, Q. M. Liu, S. L. Chen, G. Y. Zhong, J. Su, L. Y. Shi, L. Tong, G. Xu, P. Gao, y, N. L. Wang. 2019-01-18. Layered semiconductor EuTe 4 with charge density wave order in square tellurium sheets. https://doi.org/10.1103/physrevmaterials.3.024002

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