Magnetic-field-induced insulator-metal transition in W-doped VO2 at 500 T.

Metal–insulator (MI) transitions in correlated electron systems have long been a central and controversial issue in material science. Vanadium dioxide (VO2) exhibits a first-order MI transition at 340 K. For more than half a century, it has been debated whether electron correlation or the structural instability due to dimerised V ions is the more essential driving force behind this MI transition. Here, we show that an ultrahigh magnetic field of 500 T renders the insulator phase of tungsten (W)-doped VO2 metallic. The spin Zeeman effect on the d electrons of the V ions dissociates the dimers in the insulating phase, resulting in the delocalisation of electrons. As the Mott–Hubbard gap essentially does not depend on the spin degree of freedom, the structural instability is likely to be the more essential driving force behind the MI transition. Vanadium dioxide exhibits a metal-insulator (MI) transition. The mechanism driving this behaviour has long been a subject of debate. Here, the authors show that the MI transition in heavily doped vanadium dioxide can be driven by a magnetic field, suggesting the MI transition is due to structural instability.