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arXiv · 2001.08020

Correlation between crystal purity and the charge density wave in 1$T$-VSe$_2$

C. J. Sayers·L. S. Farrar·S. J. Bending·M. Cattelan·A. J. H. Jones·N. A. Fox·G. Kociok-Köhn·K. Koshmak·J. Laverock·L. Pasquali·E. Da Como
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Abstract

We examine the charge density wave (CDW) properties of 1$T$-VSe$_{2}$ crystals grown by chemical vapour transport (CVT) under varying conditions. Specifically, we find that by lowering the growth temperature ($T_{\mathrm{g}}$ $<$ 630$^{\circ}$C), there is a significant increase in both the CDW transition temperature and the residual resistance ratio (RRR) obtained from electrical transport measurements. Using x-ray photoelectron spectroscopy (XPS), we correlate the observed CDW properties with stoichiometry and the nature of defects. In addition, we have optimized a method to grow ultra-high purity 1$T$-VSe$_{2}$ crystals with a CDW transition temperature, $T_{\mathrm{CDW}}$ = (112.7 $\pm$ 0.8) K and maximum residual resistance ratio (RRR) $\approx$ 49, which is the highest reported thus far. This work highlights the sensitivity of the CDW in 1$T$-VSe$_{2}$ to defects and overall stoichiometry, and the importance of controlling the crystal growth conditions of strongly-correlated transition metal dichalcogenides.

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C. J. Sayers, L. S. Farrar, S. J. Bending, M. Cattelan, A. J. H. Jones, N. A. Fox, G. Kociok-Köhn, K. Koshmak, J. Laverock, L. Pasquali, E. Da Como. 2020-01-22. Correlation between crystal purity and the charge density wave in 1$T$-VSe$_2$. https://doi.org/10.1103/physrevmaterials.4.025002

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