On semiconductor--metal transition in FeSi induced by ultrahigh magnetic field

TL;DR

This paper investigates the discrepancy in reported critical magnetic fields for the semiconductor-metal transition in FeSi, analyzing measurement techniques and emphasizing the complex, wide-range nature of the transition under ultrahigh magnetic fields.

Contribution

It provides a methodological analysis explaining differences in experimental results and highlights the complex behavior of FeSi's transition over a broad magnetic field range.

Findings

Discrepancies in critical magnetic field estimates are due to different measurement techniques.

Inductive and RF methods complement each other in studying the transition.

The transition occurs over a wide magnetic field range, not at a single field value.

Abstract

At low temperatures, iron monosilicide is a strongly correlated narrow-gap semiconductor. A first order transition to metal state induced by magnetic field was observed for the first time at 355 T in Ref. [Yu. B. Kudasov et al., JETP Lett. 68 (1998) 350]. However, recently a smooth transition from 230 T to 270 T was found under similar conditions in Ref. [D. Nakamura et al., Phys. Rev. Lett. 127 (2021) 156601]. This discrepancy goes far beyond experimental errors and deserves a careful study. A methodological analysis of inductive and RF techniques of conductivity measurements shows that the difference of these critical magnetic field estimations stems from a divergence in dynamic ranges of the techniques. In fact, the above mentioned methods supplement each other. The semiconductor-metal transition under magnetic field in FeSi is a complex phenomenon which occurs at the wide range of magnetic fields.