Pressure–Temperature Phase Diagram of Vanadium Dioxide

Abstract

equally to this work. AbstractThe complexity of strongly correlated electron physics in vanadium dioxide is exemplified as its rich phase diagrams of all kinds, which in turn shed light on the mechanisms behind its various phase transitions. In this work, we map out the hydrostatic pressuretemperature phase diagram of vanadium dioxide nanobeams by independently varying pressure and temperature with a diamond anvil cell. In addition to the well-known insulating M1 (monoclinic) and metallic R (tetragonal) phases, the diagram identifies the existence at high pressures of the insulating M1' (monoclinic, more conductive than M1) phase, and two metallic phases of X (monoclinic) and O (orthorhombic, at high temperature only). Systematic optical and electrical measurements combined with density functional calculations allow us to delineate their phase boundaries as well as reveal some basic features of the transitions.

Ultrafast response of photoexcited carriers in VO2 at high-pressure

“…Finally, m 1 almost vanishes at high pressures ( figure 3(b)) indicating that the WLS merge with the QP. We emphasize that the proposed band diagram not only explains our experimental observations, but is also consistent with recent resistivity measurements that demonstrate the thermally activated character of the conductivity below T c for pressures up to 20 GPa [36,47]. The resistivity behavior implies only the existence of an energy gap leading to the decrease in the number of thermally activated charge carriers upon cooling.…”

“…Figure 4(c) shows the frequencies of Raman modes as a function of pressure. The kinks around 12 GPa indicating an isostructural phase transition to a monoclinic M1′ phase [33,35] are in agreement with previous Raman studies [32,35,36], where transition pressures of 10-16 GPa are reported. Thus, our Raman results clearly indicate that VO 2 preserves monoclinic structure up to the highest pressure applied in our experiments.…”

“…Most probably this difference is related to the stiffening of the dimerized lattice structure under pressure [32,35]; that makes the vanadium dimers even more stable, and thus raises the energy barrier to the metallic rutile phase. The observed increase of Φ th with pressure is consistent with the recently reported growth of T c in VO 2 under pressure and the estimations of the corresponding increase in the latent heat of the IMT [36].…”

“…Application of external pressure offers an attractive way to distinguish the influence of the structural instability from the correlation effects on the IMT in VO 2 . At a critical pressure between 10 and 16 GPa at room temperature VO 2 undergoes an isostructural transformation which preserves the dimerized monoclinic structure [32][33][34][35][36]. In addition, infrared spectroscopy suggests band gap filling above 10 GPa [32].…”

Development of VO2‐Nanoparticle‐Based Metal–Insulator Transition Electronic Ink

“…[1][2][3] Vanadium oxides usually possess several oxide phases, including VO, VO 2 , V 2 O 3 , V 2 O 5 , V 3 O 7 , V 4 O 9 , and V 6 O 13 . Vanadium oxide is among these smart materials which can tune its electrical and optical properties by applying external stimuli, such as heat or pressure.…”