Low-temperature hopping and absence of spin-dependent transport in single crystals of cobalt-doped ZnO

摘要: Long needle-shaped single crystals of Zn1-xCoxO were grown at low temperatures using a molten salt solvent technique, up to x=0.10. The conduction process is determined be by Mott variable range hopping. Both pristine and cobalt doped clearly exhibit crossover from negative positive magnetoresistance as the temperature decreased. increases with increased Co concentration reaches 20% (2.5 K) high fields (>1 T). SQUID magnetometry confirms that are predominantly paramagnetic in nature magnetic response independent concentration. results indicate doping crystalline ZnO introduces localized electronic states isolated Co2+ ions into host matrix, but magnetotransport properties decoupled.