反铁磁半金属GdSb中极大磁电阻效应研究
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摘要
具有极大磁电阻的半金属材料因其可能具有非寻常的拓扑电子结构、电输运特性,可为高能物理相关的狄拉克费米子、外尔费米子以及马约拉纳费米子的研究提供崭新的舞台,受到了广泛关注.本文通过助溶剂法合成高质量的GdSb单晶并系统地研究其结构、磁性、电输运等性质,发现该材料具有NaCl型晶体结构(空间群Fm-3m),并且在23.4 K附近经历反铁磁相变.电输运结果表明GdSb具有金属导电性,自旋无序效应可导致磁相变温度附近的电阻出现异常.更吸引人的是,样品在磁场(H=9 T)作用下,低温(2 K)电阻将出现平台,展示出极大的磁电阻效应(MR=12 100%).通过霍尔效应及第一性原理计算,发现GdSb是多带及补偿型半金属,其中电子与空穴的数目相当.电子-空穴补偿及较大的载流子迁移率是极大磁电阻的来源.
Semimetals with colossal magnetoresistance have attracted a significant interest because of not only their possible nontrivial electronic structures, and unusual transport properties, but also the deep connections to the high-energy physics. The authors of this paper synthesize the GdSb single crystal and systematically characterize its crystal structure, magnetism, and electric transport properties. It is found that this compound crystallizes in NaCl-type structure with a space group Fm-3 m, and experiences antiferromagnetic phase transition at 23.4 K. Electric transport measurement reveals that the compound is metallic, in which spin disorders induce a resistivity anomaly emerging around its magnetic transition temperature. Intriguingly, obvious resistivity plateaus are observed at a low temperature, when the compound is subjected to the external magnetic field, showing colossal magnetoresistance effect up to 12 100% at 2 K and 9 T. Through Hall resistivity measurement and first-principles band structure calculations, GdSb is believed to be a multi-band and compensated semimetal, in which the total carrier concentrations of electrons and holes are almost comparable. The electron-hole compensation and ultrahigh mobility of GdSb can be attributed to the colossal magnetoresistance in this compound.
Semimetals with colossal magnetoresistance have attracted a significant interest because of not only their possible nontrivial electronic structures, and unusual transport properties, but also the deep connections to the high-energy physics. The authors of this paper synthesize the GdSb single crystal and systematically characterize its crystal structure, magnetism, and electric transport properties. It is found that this compound crystallizes in NaCl-type structure with a space group Fm-3 m, and experiences antiferromagnetic phase transition at 23.4 K. Electric transport measurement reveals that the compound is metallic, in which spin disorders induce a resistivity anomaly emerging around its magnetic transition temperature. Intriguingly, obvious resistivity plateaus are observed at a low temperature, when the compound is subjected to the external magnetic field, showing colossal magnetoresistance effect up to 12 100% at 2 K and 9 T. Through Hall resistivity measurement and first-principles band structure calculations, GdSb is believed to be a multi-band and compensated semimetal, in which the total carrier concentrations of electrons and holes are almost comparable. The electron-hole compensation and ultrahigh mobility of GdSb can be attributed to the colossal magnetoresistance in this compound.
引文
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[2]RAMIREZ A P.Colossal magnetoresistance[J].J Phys:Condens Matter,1997,9:8171.
[3]TSYMBAL E Y,MRYASOV O N,LECLAIR P R.Spin-dependent tunnelling in magnetic tunnel junctions[J].J Phys:Condens Matter,2003,15:R109.
[4]LIANG T,GIBSON Q,ALI M N,et al.Ultrahigh mobility and giant magnetoresistance in the Dirac semimetal Cd3As2[J].Nature mater,2015,14:280.
[5]XIONG J,KUSHWAHA S K,LIANG T,et al.Evidence for the chiral anomaly in the Dirac semimetal Na3Bi[J].Science,2015,350:413-416.
[6]WENG H,FANG C,FANG Z,et al.Weyl semimetal phase in noncentrosymmetric transition-metal monophosphides[J].Phys Rev X,2015,5:011029.
[7]ALI M N,XIONG J,FLYNN S,et al.Large,non-saturating magnetoresistance in WTe2[J].Nature,2014,514:205.
[8]DENG K,WAN G,DENG P,et al.Experimental observation of topological Fermi arcs in type-II Weyl semimetal MoTe2[J].Nature Phys,2016,12(12):1105.
[9]TAFTI F F,GIBSON Q D,KUSHWAHA S K,et al.Resistivity plateau and extreme magnetoresistance in LaSb[J].Nature Phys,2016,12(3):272.
[10]TAFTI F F,GIBSON Q,KUSHWAHA S,et al.Temperature-field phase diagram of extreme magnetoresistance[J].Proc Natl Acad Sci USA,2016,113:E3475.
[11]DU X,TSAI S W,MASLOV D L,et al.Metal-insulator-like behavior in semimetallic bismuth and graphite[J].Phys Rev let,2005,94:166601.
[12]HOU Z,WANG W,XU G,et al.High electron mobility and large magnetoresistance in the half-Heusler semimetal LuPtBi[J].Phys Rev B,2015,92(23):235134.
[13]EMMANOUILIDOU E,SHEN B,DENG X,et al.Magnetotransport properties of the single-crystalline nodal-line semimetal candidates CaTX(T=Ag,Cd;X=As,Ge)[J].Phys Rev B,2017,95:245113.
[14]SUN S,WANG Q,GUO P J,et al.Large magnetoresistance in LaBi:origin of field-induced resistivity upturn and plateau in compensated semimetals[J].New J Phys,2016,18:082002.
[15]SONG J J,TANG F,ZHOU W,et al.Extremely large magnetoresistance in the antiferromagnetic semimetal GdSb[J].JMater Chem C,2018,6:3026-3033.