Semiconductor–metal transition in FeSi in ultrahigh magnetic field

Abstract We study the conductivity and magnetic susceptibility of single-crystal iron monosilicide under ultra high magnetic field at 4.2 and 77 K. At 77 K we detect a gradual increase of conductivity by more than a factor of 100 as the magnetic field gets stronger. At 4.2 K we observe the first-order semiconductor–metal phase transition in the field of 355 T. The transition was accompanied by a step of magnetic moment by 0.95μ B per iron atom. The nature of the transition is discussed.