(Y_(2-x)Pb_(x))Ru_(2)O_(7)中金属-绝缘体转变调控研究  

Study on the modulation of metal-insulator transition in(Y_(2-x)Pb_(x))Ru_(2)O_(7)system

作　　者：焦媛媛 JIAO Yuanyuan(College of Science,Wuhan University of Science and Technology,Wuhan 430065,China)

机构地区：[1]武汉科技大学理学院,湖北武汉430065

出　　处：《武汉科技大学学报》2024年第3期161-165,共5页Journal of Wuhan University of Science and Technology

基　　金：国家自然科学基金项目(11904272);武汉科技大学冶金工业过程系统科学湖北省重点实验室开放基金项目(Z202202).

摘　　要：烧绿石结构的Y 2 Ru_(2)O_(7)表现为反铁磁Mott绝缘体基态,而具有相同结构的Pb_(2)Ru_(2)O_(6.5)则呈现顺磁金属基态。为深入理解此差异,本研究采用固相反应法合成(Y_(2-x)Pb_(x))Ru_(2)O_(7)系列多晶材料,并系统研究了Pb^(2+)掺杂浓度x对其晶体结构和电阻率、磁化率等物理性质的影响。结果表明,(Y_(2-x)Pb_(x))Ru_(2)O_(7)(0≤x≤2.0)材料在x=0.5时经历了金属-绝缘体转变。通过与类似结构的烧绿石氧化物对比后发现,Pb^(2+)替代Y^(3+)不仅引入了额外的载流子,其6s^(2)存在的孤对电子还可能增强费米面附近的态密度,这两个因素的综合作用可能是其出现金属-绝缘体转变的原因。该类4d/5d烧绿石氧化物为研究受到强烈几何挫折的关联电子奇异物性提供了关键的材料平台。The pyrochlore-structured Y_(2)Ru_(2)O_(7) exhibits anti-ferromagnetic Mott insulating ground state,while Pb_(2)Ru_(2)O_(6.5) with a similar structure displays a paramagnetic metallic ground state.To elucidate this disparity,this study synthesized a series of(Y_(2-x)Pb_(x))Ru_(2)O_(7) polycrystalline materials by solid-state reaction method,and systematically analyzed the effects of Pb doping content on the crystal structure and resistivity and magnetization properties of the materials.The results indicate that(Y_(2-x)Pb_(x))Ru_(2)O_(7)(0≤x≤2.0)mateirals undergo metal-insulator transition at x=0.5.Comparative analysis with pyrochlore oxides of similar structure reveals that,the substitution of Pb^(2+) for Y^(3+) introduces additional carriers,and the lone pair electrons in the 6s^(2) of Pb^(2+) might enhance the density of states near the Fermi surface.The combined effect of these factors appears to be the underlying cause for the metal-insulator transition observed.These findings suggest that the 4d/5d pyrochlore oxides provide a pivotal material platform for investigating the anomalous properties of correlated electrons under strong geometric frustration.

关 键 词：烧绿石 金属-绝缘体转变 Pb^(2+)掺杂 Y_(2)Ru_(2)O_(7) 

分 类 号：O469[理学—凝聚态物理]