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Electronic Transport Properties of Nb1–xTaxSb2 Single-Crystal Semimetals Grown by a Chemical Vapor Transport Based High-Throughput Method

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journal contribution
posted on 2020-12-22, 21:14 authored by Lei Guo, Meng Xu, Lei Chen, Xin Huang, Xin-Yao Shi, Jing-Shi Ying, Tao Zhang, Weiyao Zhao, Shuai Dong, Ren-Kui Zheng
In quantum materials, the Fermi surface and physical behaviors are particularly sensitive to the crystal quality and composition, while it is difficult to obtain a large quantity of quasi-continuous stoichiometric ratio high-quality single crystals quickly, which seriously restricts the research efficiency and scientific achievement transformation. In the past decade, the rise of high-throughput technologies has brought new opportunities to the exploration and mechanism cognition of topological quantum materials. Taking Nb1–xTaxSb2 (NTS) topological semimetals as an example, here we propose a high-throughput single-crystal growth and design method based on chemical vapor transport (CVT) for high-melting-point transition-metal dichalcogenide materials, which intends to accelerate the crystal synthesis and the research efficiency by the influence of different proportions on the properties of the quantum systems. We have successfully grown Nb1–xTaxSb2 single crystals of various proportions (x = 0, 0.1, 0.2, 0.3, 0.5, 0.7, 0.8, 0.9, 1) in one pot at one time with the help of a CVT-based high-throughput method. Then, we systematically study the effect of composition on its crystallographic and magnetotransport properties. First, the excellent crystallographic quality and element uniformity of the produced NTS were verified via X-ray diffraction, energy dispersive X-ray spectroscopy, and transmission electron microscopy. Later, we performed temperature- and angle-dependent resistivity measurements on the as-grown NTS crystals under magnetic fields up to B = 9 T and found the following. (1) The resistivity of all NTS crystals decreases monotonically with decreasing temperature from T = 300 K under zero magnetic field and displays resistivity plateaus below T = 10 K. (2) Upon application of a magnetic field larger than 3 T the resistivity shows a significant upturn in the low-temperature regions for NbSb2 and TaSb2. This resistivity upturn, however, is rapidly suppressed with an increase in x from 0 to 0.5, completely disappears for x = 0.5, and recovers with a further increase in x from 0.5 to 1. (3) All NTS crystals show anisotropic parabolic-like magnetoresistance behaviors with no sign of saturation. (4) The magnetoresistance highly depends on the Nb:Ta ratio and reaches a minimum value when the Nb:Ta ratio is 1. An analysis of the results reveals that the degree of Nb:Ta atomic disorder and the electron–hole compensation could account for the doping-dependent magnetotransport behaviors. In conclusion, our method does have high-throughput characteristics, and the results not only provide further insight into the electronic transport properties of the NTS family but also give a reliable reference for other similar systems, which may promote the opening of a new chapter of a high-throughput research mode in quantum materials.

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