Hall carrier density and magnetoresistance measurements in thin-film vanadium dioxide across the metal-insulator transition

Temperature-dependent magnetotransport measurements in magnetic fields of up to 12 T were performed on thin-film vanadium dioxide $\left({\text{VO}}_2\right)$ across the metal-insulator transition (MIT). The Hall carrier density increases by 4 orders of magnitude at the MIT and accounts almost entirely for the resistance change. The Hall mobility varies little across the MIT and remains low, $\sim 0.1{\text{cm}}^2/\text{V}\text{sec}$. Electrons are found to be the major carriers on both sides of the MIT. Small positive magnetoresistance in the semiconducting phase is measured.

Figure 1

(Color online) XRD spectrum from a ${\text{VO}}_2$ thin film on $\text{Si}\left(001\right)/{\text{SiO}}_2\left(\text{native}\text{oxide}\right)$ substrate. $d$ values (in $\text{Å}$) of the peaks are inscribed and for ${\text{VO}}_2$ lines corresponding Miller indices of the Bragg planes are given in brackets according to Ref. 21.

Figure 2

(Color online) (a) Photo of ${\text{VO}}_2$ sample mounted on a copper base and set up for Hall measurements. Dark clover-leaf pattern is a ${\text{VO}}_2$ film on transparent square sapphire substrate of $1\text{cm}\times 1{\text{cm}}^2$ size. (b) The Hall voltage $V_{13}$ in the metallic [upper line of data marks (red online)] and semiconducting [lower line of data marks (blue online)] states.

Figure 3

(Color online) Electron transport properties of a thin-film ${\text{VO}}_2$ on an ${\text{Al}}_2{\text{O}}_3$ substrate (sample A) measured by 12 T sweeping field apparatus. The Hall-coefficient sign corresponds to electrons as the dominant current carriers.

Figure 4

(Color online) Carrier density of a ${\text{VO}}_2$ film measured using 1.4 T fixed field apparatus. The resistivity of the film is displayed in the inset.