Evidence for magnetic order in graphite from magnetization and transport measurements

Abstract

This chapter reviews the experimental evidence obtained for the existence of magnetic order triggered by defects and/or non-magnetic ions in graphite with very low magnetic impurities concentrations. We demonstrate how and where this magnetically ordered state is produced in graphite bulk, thin flakes and powders in a reproducible manner. The experimental evidence obtained in the last 12 years leaves no doubt that this ferro-or ferrimagnetism is intrinsic of the graphite structure containing certain defects and not related to magnetic impurities. The main aim of this chapter is to provide the reader the key experimental facts and characterisation methods necessary to arrive at such a conclusion. We restrict the discussion to results obtained from two main magnetic characterisation methods, namely magnetization and transport measurements. In addition, we describe in Sect. 3.2 the main characterization method for trace element analysis to obtain the magnetic and nonmagnetic impurities concentration. The chapter is concluded with an overview of further, independently obtained evidence for magnetic order in graphitic materials from literature.