Field driven Metal-Insulator transition in rhombohedral Bismuth and Arsenic crystals

TL;DR

This study investigates the magnetic field-driven metal-insulator transition in rhombohedral Bismuth and Arsenic crystals, revealing unique re-entrant behavior in Bismuth and giant magnetoresistance, with explanations based on excitonic and Bose metal correlations.

Contribution

It provides a microscopic model explaining the unusual field-driven MIT and re-entrant behavior in Bismuth, incorporating excitonic and preformed pair scenarios.

Findings

Re-entrant insulator-metal transition observed in Bismuth at high magnetic fields.

Giant magnetoresistance (~10^5%) detected at low temperatures in both crystals.

Unusual Kohler scaling indicates increased carrier density due to exciton melting.

Abstract

The metal to insulator (MIT) transition is accompanied by huge changes in physical responses by the control and tuning of experimental parameters like doping, pressure, chemical composition, and magnetic field. Here, we study the magnetic field-driven MIT for two pnictides in their elemental form, namely Arsenic and Bismuth. At low temperatures, Bismuth shows an unusual behaviour of a re-entrant IMT at high fields in addition to a higher temperature MIT at smaller fields. However, Arsenic shows the commonly observed single MIT. The Shubnikov de Haas (SdH) oscillations are observed for both As and Bi below 10 K. Giant magneto-resistance of the order of ~105 (MR%) is observed for both crystals at 2 K and 14 Tesla transverse magnetic field. The unusual Kohler scaling behaviour of MR at low temperature indicate the presence of increased carrier density attributed to the melting of excitons. Based on a microscopic model, the microscopic processes underpinning the unusual features of a field-driven MIT and re-entrant IMT, along with the relevance of both excitonic and Bose metal correlations near these incipient instabilities, are qualitatively described in the framework of field-driven excitonic condensate and Das-Doniach preformed pair scenarios in one single picture.