Magnetic-field induced superconductor-metal-insulator transitions in bismuth metal-graphite

TL;DR

This study investigates magnetic-field-induced phase transitions in bismuth-metal graphite, revealing superconductor-metal-insulator transitions, localized electron effects, and weak localization phenomena through resistivity and susceptibility measurements.

Contribution

It provides new insights into magnetic-field-driven phase transitions and localization effects in bismuth-metal graphite with layered nanostructures.

Findings

Superconductivity below 2.48 K due to Bi nanoparticles.

Magnetic-field induced transition from metallic to semiconductor-like phase around 25 kOe.

Evidence of weak localization effects from magnetoresistance and temperature dependence.

Abstract

Bismuth-metal graphite (MG) has a unique layered structure where Bi nanoparticles are encapsulated between adjacent sheets of nanographites. The superconductivity below $T_{c}$ (= 2.48 K) is due to Bi nanoparticles. The Curie-like susceptibility below 30 K is due to conduction electrons localized near zigzag edges of nanographites. A magnetic-field induced transition from metallic to semiconductor-like phase is observed in the in-plane resistivity $\rho_{a}$ around $H_{c}$ ($\approx$ 25 kOe) for both $H$$\perp$$c$ and $H$$\parallel$$c$ ($c$: c axis). A negative magnetoresistance in $\rho_{a}$ for $H$$\perp$$c$ (0$<H\leq$3.5 kOe) and a logarithmic divergence in $\rho_{a}$ with decreasing temperature for $H$$\parallel$$c$ ($H$ $>$ 40 kOe) suggest the occurrence of two-dimensional weak localization effect.