Three-dimensional quasi-quantized Hall insulator phase in SrSi2

TL;DR

This paper reports the discovery of a three-dimensional quasi-quantized Hall insulator phase in SrSi2, where the Hall conductivity approaches a quantized value while the longitudinal resistivity diverges at low temperatures, revealing novel quantum Hall physics in 3D.

Contribution

It provides experimental evidence for a 3D quasi-quantized Hall insulator phase in SrSi2, extending quantum Hall phenomena beyond 2D systems.

Findings

Longitudinal resistivity diverges at low temperature.

Hall conductivity approaches a quasi-quantized value.

The phase occurs in a magnetic-field induced insulating state.

Abstract

In insulators, the longitudinal resistivity becomes infinitely large at zero temperature. For classic insulators, the Hall conductivity becomes zero at the same time. However, there are special systems, such as two-dimensional quantum Hall isolators, in which a more complex scenario is observed at high magnetic fields. Here, we report experimental evidence for a quasi-quantized Hall insulator in the quantum limit of the three-dimensional semimetal SrSi2. Our measurements reveal a magnetic field-range, in which the longitudinal resistivity diverges with decreasing temperature, while the Hall conductivity approaches a quasi-quantized value that is given only by the conductance quantum and the Fermi wave vector in the field-direction. The quasi-quantized Hall insulator appears in a magnetic-field induced insulating ground state of three-dimensional materials and is deeply rooted in quantum Hall physics.