sr0.9K0.1Zn1.8Mn0.2As2_ 一个具有巨磁阻效应的铁磁半导体.docVIP

  Sr0.9K0.1Mn0.2As2: a ferromagnetic semiconductor with colossal magnetoresistence YANG Xiaojun, Tao Qian, CAO Guanghan, XU Zhuan** 5 10 15 20 25 30 35 40 (Department of Physics, Zhejiang University, Hangzhou 310027) Abstract: (Sr,K)(Zn,Mn)2As2 was found to be a bulk diluted magnetic semiconductor system with decoupled charge and spin doping through K+ for Sr2+ and isovalent Mn2+ for Zn2+ substitution. The doped SrZn2As system has ahexagonal CaAL2Si2-type structure with the Zn2As2 layer forming a honeycomb-like network. Magnetization measurements show that the samples undergo ferromagnetic transitions with a Curie temperature of 23 K and saturation moment about 1.5 μB/Mn. Surprisingly, colossal negative magnetoresistance (MR), defined as [ρ(H)?ρ(0)]/ρ(0), up to ?99.8% was also observed in this system. The discovery should bring new excitement to this field and make the recently discovered bulk DMSs truly appealing class of systems. With decoupled charge and spin doping, this system combines semiconductor, ferromagnetism and colossal magnetoresistance (CMR), which make it appealing not only for theoretic study but also for application. Key words: condensed matter physics; diluted magnetic semiconductor; magnetoresistance; SrZn2As 0 Introduction Combining semiconductor and magnetism, diluted magnetic semiconductors (DMS) add the spin of carriers to electronic, which have attracted much attention because DMS may not only exhibit substantial novel phenomena such as quantum Hall effects, semiconductor lasers and single-electron charging, but also bring about numerous applications in sensors, memories as well as spintronics. [1~5]However, III-V based DMS materials, represented by (Ga,Mn)As, obtained by heterovalent substitution of Mn2+for Ga3+ are only available as thin films due to the limited chemical solubility of manganese in GaAs ( 1%), and lack independently controlling of local moment and carrier densities. [6, 7] I-II-V based Li(Zn,Mn)As was theoretically pro