Magnetic-field-induced insulator–metal transition in W-doped VO2 at 500 T
Yasuhiro H. Matsuda, Daisuke Nakamura, Akihiko Ikeda, S. Takeyama, Yuki Suga, Hayato Nakahara, Yuji Muraoka
Abstract
Abstract Metal–insulator (MI) transitions in correlated electron systems have long been a central and controversial issue in material science. Vanadium dioxide (VO 2 ) 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 VO 2 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.