三元钯基碲化物的单晶生长和电输运性质

Crystal growth and electronic transport property of ternary Pd-based tellurides

三元过渡金属硫属化物是一类兼具低维结构和强关联电子的系列化合物,依其不同构成呈现出丰富多彩的电子基态.在硫属元素(S,Se,Te)中,Te具有比S和Se更小的电负性和更大的原子质量,因而过渡金属碲化物呈现出与硫化物和硒化物不同的晶体结构、电子结构和物理性质.三元过渡金属碲化物中陆续被发现新超导体Ta_(4)Pd_(3)Te_(16)和Ta_(3)Pd_(3)Te_(14),拓扑狄拉克半金属TaTMTe_(5)(TM=Pd,Pt,Ni)等,进一步拓展了碲化物家族的物性研究,为该材料体系的潜在应用探究奠定了基础.本文首先介绍了利用自助熔剂法和化学气相输运法生长4种三元钯基碲化物(Ta_(4)Pd_(3)Te_(16),Ta_(3)Pd_(3)Te_(14),TaPdTe_(5)和Ta_(2)Pd_(3)Te_(5))单晶的详细方案,并给出了化学气相输运法生长Ta_(2)Pd_(3)Te_(5)的化学反应方程式.生长出的Ta_(4)Pd_(3)Te_(16)和Ta_(3)Pd_(3)Te_(14)晶体的超导转变宽度仅分别为0.57 K和0.13 K,通过电阻数据拟合,得到了拓扑绝缘体Ta_(2)Pd_(3)Te_(5)晶体的能隙值为23.37 meV.最后,本文对利用自助熔剂法生长上述4种三元钯基碲化物晶体的生长条件和规律进行了对比分析和讨论,可以为采用类似方法生长其他过渡金属碲化物晶体提供启发和借鉴.

Ternary transition-metal chalcogenides are a series of compounds that possess both low-dimensional structures and correlated electrons,and display rich electronic ground states,depending on their different compositions.Among the chalcogen(S,Se,Te),Te has lower electronegativity and heavier atomic mass than S and Se.Thus,transition-metal tellurides take on distinct crystal structures,electronic structures and physical properties.In recent years,we have successively discovered novel superconductors Ta_(4)Pd_(3)Te_(16) and Ta_(3)Pd_(3)Te_(14),topological Dirac semimetals TaTMTe_(5)(TM=Pd,Pt,Ni),etc.,further expanding the investigations of physical properties of the family of tellurides and laying a foundation for exploring their potential applications.The basis of further investigating and exploring the potential applications is the obtaining of the high-quality crystals with large dimensions.In this work,we first introduce the whole procedures of the single-crystal growth in growing the four ternary Pd-based tellurides(Ta_(4)Pd_(3)Te_(16),Ta_(3)Pd_(3)Te_(14),TaPdTe_(5),and Ta_(2)Pd_(3)Te_(5))by employing the self-flux method and chemical vapor transport method,and then give the chemical reaction equations in chemical vapor transport.The superconducting transition width of the Ta_(4)Pd_(3)Te_(16) crystal and Ta_(3)Pd_(3)Te_(14) crystal are as small as 0.57 K and 0.13 K,respectively,and by fitting the temperature-dependent resistivity of the topological insulator Ta_(2)Pd_(3)Te_(5),the band gap is derived to be 23.37 meV.Finally,we comparatively analyse the crystal-growth processes of the four ternary Pd-based tellurides by employing the flux method,which can provide the inspiration and reference for growing the crystals of other transition-metal tellurides by employing the similar methods.