准一维电荷有序半导体(NbSe_(4))_(3)I低温物性研究  

Physical Properties of Quasi-one Dimensional Charge-Ordered Semiconductor (NbSe_(4))_(3)I at Low Temperature

作　　者：刘步 安超 周颖 张敏 杨昭荣 LIU Bu;AN Chao;ZHOU Ying;ZHANG Min;YANG ZhaoRong(Information Materials and Intelligent Sensing Laboratory of Anhui Province,Institutes of Physical Science and Information Technology,Anhui University,Hefei 230601,China;Key Laboratory of Structure and Functional Regulation of Hybrid Materials(Anhui University),Ministry of Education,Hefei 230601,China;Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions,High Magnetic Field Laboratory,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China)

机构地区：[1]安徽大学,物质科学与信息技术研究院,信息材料与智能感知安徽省实验室,合肥230601 [2]安徽大学,杂化材料结构与功能调控教育部重点实验室,合肥230601 [3]中国科学院合肥物质科学研究院,强磁场科学中心,极端条件凝聚态物理安徽省重点实验室,合肥230031

出　　处：《低温物理学报》2021年第1期18-25,共8页Low Temperature Physical Letters

基　　金：国家重点基础研究发展计划(批准号:2018YFA0305704,2016YFA0401804);国家自然科学基金(批准号:U19A2093,12004004,11874362);安徽省自然科学基金(批准号:1908085QA18,2008085QA40)资助的课题.

摘　　要：近期,准一维电荷密度波(CDW)材料(TaSe_(4))_(2)I的低温相被报道为轴子绝缘体[Nature 575,315(2019)],引起了广泛的关注.电荷有序半导体(NbSe_(4))_(3)I与(TaSe_(4))_(2)I属于同一个体系,晶体结构也表现为准一维的链状结构,低温下的物态值得进一步研究.本工作利用拉曼光谱和电输运测量实验方法对化学气相输运法(CVT)制备的高质量type-II(NbSe_(4))_(3)I单晶样品进行了低温下的电输运和振动性质研究.通过实验研究发现,(NbSe_(4))_(3)I在低温下并不存在轴子绝缘态.此外,电输运实验表明(NbSe_(4))_(3)I在TC1=270.4 K处发生了第一次结构相变,即P4/mnc(D64h)→P421c(D42d).随温度进一步降低,拉曼光谱测试发现在TC2=180 K和TC3=110 K附近有新峰的出现,分别归因于反铁电(AFE)长程有序相的形成而导致的第二次结构相变以及对称性进一步降低导致的第三次结构相变.值得一提的是,与其他拉曼峰的演化不同,57.4 cm^(-1)右侧出现的新峰在TC3以下迅速向高波数移动,发生明显的蓝移,且伴随强度的急剧增强,有可能在低温温度传感器领域有着潜在的应用前景.Recently,quasi-one-dimensional(Q1D)material(TaSe_(4))_(2)I was reported to bean axion insulator since it enters into the charge density wave(CDW)state[Nature 575,315(2019)],which attracts wide research of interest.As the sister compound of(TaSe_(4))_(2) I,charge-ordered semiconductor (NbSe_(4))_(3)I also exhibits the Q1D chain-like crystal structure,and thus its physical properties deserve further investigation.In this paper,we study the electrical transport and vibrational properties of as-grown type-II (NbSe_(4))_(3)I single crystal through Raman spectra and electrical transport measurements.The axion insulator is not observed in (NbSe_(4))_(3) I.In addition,new peaks in Raman spectra are observed at 180 K and 110 K.After carefully analysis,the new peaks appeared at 180 K are ascribed to the second structural phase transition accompanied with formation of long-range antiferroelectric(AFE)order and the peaks showed at 110 K are attributed to the third structural phase transition.Moreover,differing from the other Raman peaks,the appeared new peak near 57.4 cm^(-1) rapidly moves toward higher frequency below 110 K,accompanied with quick enhancement of intensity,which may have potential applications in temperature sensors.

关 键 词：(NbSe_(4))_(3)I 准一维材料 拉曼散射 I-V 曲线 

分 类 号：O472[理学—半导体物理]