新型超导体MgB_2的热电势和电阻率研究

测量了MgB-2的热电势和电阻率与温度的依赖关系.在100K—300K区间，热电势呈近似线性温度依赖关系，其斜率为正，表明载流子为空穴型且与能带贡献的图像相一致.与此对应，在此温区电阻率呈T2依赖关系.在100K以下，热电势和电阻率各自转变了其高温区的温度依赖关系.热电势在超导转变温度Te(零电阻36.6K)到100K间有一宽峰，具有声子曳引峰的特征，表明电子-声子相互作用很强.估算了一些重要的参数，如带米能EF、能带宽度等.

STUDY ON THE THERMOPOWER AND RESISTIVITY OF A NEW SUPERCONDUCTOR MgB_2

The temperature-dependent thermopower and resistivity of MgB-2 were measured.In the range of 100—300K, the thermopower presents positive nearly linear temperature dependence,indicating that the charge carrier is hole and it is consistent with the energy band pattern.In contrast,the resistivity follows T+2 relationship in the same temperature range.Below 100K,thermopower and resistivity change their temperature dependence.The thermopower presents a hump between the superconducting transition temperature T-c (zero resistance,36.6K) and 100K.It has the characteristic of the phonon drag,indicating the strong electron-phonon interaction.Some important parameters are estimated according to experimental results,such as Fermi energy E-F and energy band width.