Single domain VO$_{2}$ single crystals exhibiting metal-insulator transition and insulator-insulator transition

Electrical transport, optical microscopy, and synchrotron-based x-ray micro-diffraction measurements have been carried out on single domain VO$_{2}$ single crystals, exhibiting an abrupt first-order metal--insulator transition (MIT) with a high resistance ratio $\sim $ 10$^{5}$ near $\sim $67 $^{\circ}$C and a gradual insulator--insulator transition (IIT) at $\sim $48 $^{\circ}$C. Low temperature (T$<$ 45 $^{\circ}$C), intermediate ($\sim $50 $^{\circ}$C $<$T$<\sim $67 $^{\circ}$C), above MIT (T$>$67 $^{\circ}$C) phases were insulating monoclinic M2 with half vanadium ion dimerization, monoclinic M1 with full vanadium ion dimerization, and rutile (R) phases, respectively. In this poster, we will present unusual structural phases of M1, M2, and R of single-domain VO$_{2}$ single crystals and discuss the relationships between structures and the characteristics of the MIT of VO$_{2}$.