新型超导体MgCNi_3的输运性质研究  

Transport properties of new superconductor MgCNi_3

作　　者：王翠焕[1] 莫维勤[1] 李世燕[1] 余旻[1] 樊荣[1] 阮可青[1] 杨宏顺[1] 曹烈兆[1] 陈仙辉[1] 

机构地区：[1]中国科学技术大学结构分析实验室,物理系合肥230026

出　　处：《物理学报》2002年第8期1816-1820,共5页Acta Physica Sinica

基　　金：国家自然科学基金 (批准号 :5 982 5 10 7)资助的课题~~

摘　　要：测量了新型超导体MgCNi3(Tc=8K)的电阻率、正常态Hall效应和热电势等输运性质 .电阻率 温度曲线表明 ,在高于 70K的温区可以用电 声子散射的Bloch Gr櫣ｎｅｉｓｅｎ公式拟合 .Hall系数RH 和热电势S在Tc 以上的整个温度范围都为负值 ,强烈表明MgCNi3的载流子类型为电子型 .RH 在从Tc 到 14 0K的温区内基本不随温度变化 ,但在14 0K到室温范围 ,RH 随温度升高其绝对值减小 ,对RH 的这种温度依赖关系进行了讨论 .S在 15 0K以上近似与温度成线性关系 ,而在 15 0K以下显示非线性 ,用电 声子相互作用的重整化效应解释了热电势的温度行为 .电阻率和热电势在 5 0K以下都表现出异常 ,显示在 5The normal state resistivtity, Hall coefficient R H and thermopower S in the new superconducting perovskite MgCNi 3 ( T c = 8 K) have been studied. Above 70K, ρ(T) fits well the curve predicted by Bloch Grüneisen theory consistently with electron phonon scattering. Both R H and S of MgCNi 3 are negative in the whole temperature range, which definitely indicates that the carrier in MgCNi 3 is the electron type. R H is temperature independent between T c and 140K. Above 140K, the magnitude of R H decreases as temperature rises. S(T) is approximately linear above 150K, while below 150K is nonlinear. It can be interpreted by the electron phonon interaction renormalization effects. An electronic crossover occurs at about 50K, resulting in the abnormal behaviour of resistivity and thermopower below 50K.

关 键 词：超导体 MGCNI3 输运性质 电阻率 热电势 Hall效应 

分 类 号：O513[理学—低温物理]