New Verbeekite-type polymorphic phase and rich phase diagram in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>PdSe</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math> system
Wenhao Liu, Mehrdad Rostami Osanloo, Xiqu Wang, Sheng Li, Nikhil Dhale, Hanlin Wu, Maarten L. Van de Put, Sabyasachi Tiwari, William G. Vandenberghe, Bing Lv
Abstract
We report a combined experimental and theoretical study of the ${\mathrm{PdSe}}_{2\ensuremath{-}x}{\mathrm{Te}}_{x}$ system. With increasing Te fraction, structural evolutions, first from an orthorhombic phase (space group Pbca) to a monoclinic phase (space group $C2/c)$ and then to a trigonal phase (space group $P\text{\ensuremath{-}}3m1)$, are observed accompanied with clearly distinct electrical transport behavior. The new monoclinic phase $(C2/c)$ belongs to the very rare Verbeekite polymorphism and is discovered within a narrow range of Te composition $(0.3\ensuremath{\le}x\ensuremath{\le}0.8)$. Electronic calculations and detailed transport analysis of the Verbeekite polymorphic ${\mathrm{PdSe}}_{1.3}{\mathrm{Te}}_{0.7}$ phase are presented. In the trigonal phase region, superconductivity with enhanced critical temperature is also observed within a narrow range of Te content $(1.0\ensuremath{\le}x\ensuremath{\le}1.2)$. The rich phase diagram, new polymorphic structure, and abnormally enhanced superconductivity could further stimulate interest to explore new types of polymorphs and investigate their transport and electronic properties in the family of transition metal dichalcogenides, which are of significant interest.