ELECTRICAL RESISTIVITY OF STAGE-1 RANDOM MIXTURE GRAPHITE INTERCALATION COMPOUNDS NEAR CRITICAL TEMPERATURES

摘要

We have measured the temperature dependence of in-plane electrical resistivity of stage-1 CocMn1-cCl2 GICs (0.70 less than or equal to c less than or equal to 1) and stage-1 CocMg1-cCl2 GICs (0.85 less than or equal to c less than or equal to 1) in the temperature range between 2.6 and 300 K. The resistivity shows a drastic increase with decreasing temperature below the critical temperature T-c for stage-1 CocMn1-cCl2 GICs (c greater than or equal to 0.85) and stage-1 CocMg1-cCl2 GICs (c greater than or equal to 0.90). The temperature dependence of this resistivity anomaly is described by a smeared power law with an exponent 2 beta, where beta is the critical exponent of spontaneous magnetization. Through the pi-d exchange interaction between pi electrons in the graphite layers and spins in the intercalate layers, the pi electrons are scattered by spin fluctuations of a virtual antiferromagnetic in-plane spin configuration arising from the superposition of two ferromagnetic in-plane structures with spin directions antiparallel to each other. [References: 5]