Correlating magnetotransport and diamagnetism ofsp2-bonded carbon networks through the metal-insulator transition

Abstract

Titanium-carbide-derived carbons (TiC-CDCs) are porous $s{p}^{2}$-bonded networks synthesized by exposing TiC to chlorine gas at an elevated temperature. The latter ``chlorination temperature'' adjusts the size of the pores and the $s{p}^{2}$-bonded carbon domains within this material. We perform magnetoresistance, electronic transport, and superconducting quantum interference device magnetization measurements on TiC-CDC samples prepared at different chlorination temperatures. Transport reveals a metal-insulator transition where high (low) chlorination temperature samples are on the metallic (insulating) side of the transition. Magnetoresistance measurements are consistent with transport in the weak and strong localization regimes for metallic and insulating samples, respectively. Changes in diamagnetism, electronic transport, and magnetoresistance data across the metal-insulator transition are coordinated, suggesting that all three properties are controlled by a single parameter, likely the expansion of $s{p}^{2}$-bonded domains.