V₂Te₂O: A Two-Dimensional van der Waals Correlated Metal

Abstract

A metastable vanadium oxytelluride V₂Te₂O is prepared via a topochemical deintercalation of interlayer Rb⁺ cations in Rb_1-δV₂Te₂O. The new ternary mixed-anion compound crystallizes in a body-centered tetragonal lattice with a = 3.9282(1) Å and c = 13.277(5) Å, containing V₂O square nets that are sandwiched by Te-atomic sheets. The charge-neutral [V₂OTe₂] block layers stack along the c axis with van der Waals forces, which shows a metallic behavior with a dominant T² dependence for resistivity at low temperatures. The electronic specific-heat coefficient reaches 33.9 mJ K^-2 mol^-1, ∼4 times that of the electronic structure calculations, suggesting a significant electron-mass renormalization. The electron correlation effect is concurrently demonstrated by the Wilson and Kadowaki-Woods ratios. Neither charge/spin-density wave nor superconductivity was observed down to 0.03 K.