LAUSR

We report thickness-tuned electrical transport in highly anisotropic three-dimensional Dirac semimetal $\mathrm{ZrT}{\mathrm{e}}_{5}$ nanosheets with thickness down to 10 nm. We find that the resistivity peak temperature ${T}^{*}$ can be significantly tuned by the nanosheet thickness. When the thickness is reduced from 160 to 40 nm, ${T}^{*}$ reduces systematically from 145 to 100 K. However, with the thickness further reducing to 10 nm, ${T}^{*}$ shifts up to a higher temperature. From our analysis, the system transitions from a topological semimetal with two types of carriers to a single band with conventional hole carriers when the thickness is less than 40 nm. Furthermore, by tracking the thickness dependence of the carrier density, we find that the Fermi level shifts continuously downward from the conduction band to the valence band with decreasing the thickness. Our experiment reveals a thickness-tuned transition of band topology in $\mathrm{ZrT}{\mathrm{e}}_{5}$ nanosheets which may be helpful for the understanding of the contrast observations in this material.