【摘要】 通过对电子型超导体Nd2-xCexCuO4(x=0.14,0.15)单晶ab面电阻率、热电势及热导的研究,发现x=0.14样品的热电势在42K附近变号,而x=0.15的热电势在整个温区都是正值,但在高温区两个样品的热电势都呈现负斜率,此现象只能归因于系统中同时存在一个电子型的能带和一个空穴型的能带。而且其电阻率行为也能用双能带模型很好的解释。随着x增加,高温区热导增加而低温区的声子峰被压低,表明载流子对热导的贡献在增加,同时声子的散射也在增加。更多还原

【Abstract】 We have presented the measurements of the in-plane resistivity, thermopower and thermal conductivity of the single crystal Nd1-xCexCuO4(x=0.14, 0.15). A sign reversal at the temperature about 42K is observed in thermopower of the sample with x=0.14, but it is positive in the whole temperature range for the sample with x=0.15. Moreover, both of the samples exhibit negative slope in the thermopower at high temperatures. All of these behaviors can be well interpreted by the two-band model with one whole band and the other electron band. At the same time, resistivity explained by the two-band model gives convincing evidence that two-band model is valid in electron-doped superconductivity. With x increasing, the thermal conductivity increases at high temperatures but decreases at low temperatures, which indicates that not only the contribution of the carriers on thermal conductivity is increasing, but also the scattering of the phonon is increasing.更多还原