Anomalous semiconducting behavior on VO₂ under high pressure

Abstract

High-pressure electrical transport properties of VO 2 have been investigated by in situ resistivity, Hall-effect, and temperature dependence of resistivity measurements. The electrical transport parameters including resistivity, Hall coefficient, carrier concentration, and mobility varies significantly around 10.4 GPa, which can be attributed to the isostructural phase transition of VO 2 . Temperature dependence of resistivity indicates that the phase transition is a semiconductor-to-semiconductor transformation, not the pressure-induced metallization as previously reported by Raman and IR experiment observations. The dramatic increase of activation energy at 10.4 GPa indicates an increasingly insulating behavior of VO 2 accompanied with the isostructural phase transition. The electrical transport properties, especially the carries transportation under compression open up a new possible basis for optimizing the performance of VO 2 based applications under ambient or extreme conditions.

Pair distribution function analysis: The role of structural degrees of freedom in the high-pressure insulator to metal transition ofVO2

“…Optical measurements identifies the onset of this transition at around 10 GPa [16]. Transport data confirm an electronic phase transition [17] and recent results suggest that VO 2 is fully metallic only above 34 GPa [18]. The nature of the P-induced IMT looks remarkably different from the T-induced IMT.…”

“…The M1 model describes very well the features of the PDF data up to 13 GPa. Around 12-13 GPa the structural transition to the HP M1 phase takes place together with the electronic transition [16][17][18]. The data collected above this pressure can still be well modeled using the M1 phase confirming that the M1 phase is a distorted monoclinic structure which retains the P 2 1 /c space group [18,19].…”

“…Indeed, an IMT is also observed applying pressure [16][17][18]. Optical measurements identifies the onset of this transition at around 10 GPa [16].…”

“…This result sheds some light on the mechanism behind the IMT in VO 2 . Although VO 2 appears to be fully metallic only above 34 GPa in the X structural phase, HP transport data show an electronic transition at 13 GPa with a reduction of the band gap and a resistance change of around 2 order of magnitude [17,18] (M phase). The M1 phase can still be used to refine the high pressure PDF data.…”

Pressure–Temperature Phase Diagram of Vanadium Dioxide

“…Transitions between these phases can be driven by temperature, photo-excitation, hydrostatic pressure, uniaxial stress, or electrical gating. 1,[4][5][6][7][8][9][10][11][12] For example, the well-known, insulating M1 (monoclinic, space group P21/c) phase transforms to the metallic R (tetragonal, P42/mnm) phase at 68 o C under ambient pressure. 1 This M1-R transition can also be driven by hydrostatic pressure 6 or uniaxial compression.…”