Co_(3)Sn_(2)S_(2)单晶的磁性和电-热输运性能  

Magnetic and electrical-thermal transport properties of Co_(3)Sn_(2)S_(2) single crystal

作　　者：祝鑫强 王剑[1] 朱璨 罗丰 陈树权 徐佳辉 徐峰[1] 王嘉赋[2] 张艳 孙志刚[1,3] Zhu Xin-Qiang;Wang Jian;Zhu Can;Luo Feng;Chen Shu-Quan;Xu Jia-Hui;Xu Feng;Wang Jia-Fu;Zhang Yan;Sun Zhi-Gang(State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan 430070,China;College of Science,Wuhan University of Technology,Wuhan 430070,China;College of Material Science and Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China)

机构地区：[1]武汉理工大学,材料复合新技术国家重点实验室,武汉430070 [2]武汉理工大学理学院,武汉430070 [3]太原科技大学材料科学与工程学院,太原030024

出　　处：《物理学报》2023年第17期298-310,共13页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12174297,12204342);国家重点研究发展计划(批准号:2018YFE0111500)资助的课题.

摘　　要：Co_(3)Sn_(2)S_(2)是一种磁性外尔半金属,具有特殊的磁性和电子结构,其独特的能带结构使其拥有反常霍尔效应、负磁阻效应和反常能斯特效应等多种物理性质.本文采用自熔剂法合成了高质量的Co_(3)Sn_(2)S_(2)单晶,并研究了Co_(3)Sn_(2)S_(2)低温下的电输运行为(磁阻效应与霍尔效应等)和热输运行为(塞贝克效应).热磁曲线表明,在居里温度点(T_(C)=178 K)以下:140K(TA)处存在特殊的磁结构,为铁磁态与反铁磁态共存的磁性过渡态.研究发现,在100—160 K出现负的反常“凸形”磁阻,且在T_(A)附近出现最大临界磁场B0,为1.41 T,同时霍尔电阻率ρ_(yx)也在T_(A)处取得最大值约20μΩ·cm.这可能是由于铁磁态与反铁磁态之间会相互竞争形成非平凡的自旋织构,导致TA附近独特的电输运行为.Co_(3)Sn_(2)S_(2)在低温下的散射机制为声学波散射和电子-声子散射的共同作用,在60—140 K时,自旋无序的增强会引起电子-声子散射增强,使得的塞贝克系数S出现平台特征.研究表明,Co_(3)Sn_(2)S_(2)在低温下的特殊磁结构和电子自旋对其电-热输运行为有着重要影响.Co_(3)Sn_(2)S_(2) is a magnetic Weyl semimetal with special magnetic and electronic structure.Its unique band structure makes it have many interesting physical properties such as abnormal Hall effect,negative magnetoresistance effect,and abnormal Nernst effect.In this work,high quality Co_(3)Sn_(2)S_(2) single crystal with a dimension of 8 mm×7 mm×0.5 mm is synthesized by self-flux method.We measure its electrical transport properties(magnetoresistance effect,Hall effect,etc.)and thermal transport properties(Seebeck effect)at low temperature.The free surface of the single crystal exhibits obvious layered growth characteristics,indicating that the Co_(3)Sn_(2)S_(2) crystal grows along the c-axis direction.The value of the normalized resistivity ρ_(3) K/ρ_(300) K for the single crystal sample at 3 K is only 0.08,indicating that the crystal quality of the sample is at a relatively high level.The thermomagnetic(M-T)curves show that a special magnetic structure near 140 K(T_(A))below the Curie temperature point(T_(C)=178 K).This special magnetic structure is a magnetic transition state in which ferromagnetic state and antiferromagnetic state coexist,making them appear as a local minimum point in the M-T curve.The Co_(3)Sn_(2)S_(2) shows a negative anomalous“convex”magnetoresistance in a large range of 100—160 K,and there exists a maximum critical magnetic field B_(0)(1.41 T),near T_(A).The coercivity H_(C) drops to almost zero at T_(A) and the Hall resistivity ρ_(yx) also reaches a maximum value of about 20μΩ·cm.This may be due to the competition between ferromagnetic state and antiferromagnetic state to form non-trivial spin texture,resulting in the unique electrical transport behavior near T_(A).When the temperature rises to T_(C),the Co_(3)Sn_(2)S_(2) undergoes a ferromagnetic phase transition,with a saturation magnetization of M_(S),anomalous Hall conductivity σ_(yx)^(A),and Hall resistivityρ_(yx) sharply decreasing.Large anomalous Hall conductance σ_(yx)^(A) and anomalous Hall angle σ_(yx)^(A)/�

关 键 词：Co_(3)Sn_(2)S_(2) 反常霍尔效应 磁阻 塞贝克效应 

分 类 号：O469[理学—凝聚态物理]