窄禁带半导体CrSb2的输运、热学和磁学性质
Transport, Thermal, and Magnetic Properties of the Narrow-Gap Semiconductor CrSb2
摘要：
电阻率，霍尔效应，塞贝克系数，热导率，热容量，和磁化率数据的CrSb 2单晶报道。尽管在100 K以下的电输运和霍尔测量中有一些不寻常的特征，但在2 ~ 750 K温度范围内只发现一个对应于T_N ~ 273 K以下长程反铁磁序的相变。许多低温特性可以解释为载流子从导带到位于导带边缘以下约16 meV的低迁移率带的热减少，如从霍尔效应数据推导出的。与Ge中发生的类似，低迁移率带可能是杂质带。在2 ~ 300 K温度范围内，Seebeck系数S为负值，从300 K时的~ -70 \muV /K到18 K时的~ 4500 \muV /K。|S|在18 K处的大的最大值可能是由于声子拖曳，其中|S|在低于18 K处由于高迁移率导带的热去布居而突然下降。10和20 K之间的大热导率（~350 W/m/K）与这种解释一致，使用完整计算的电子结构对塞贝克系数进行的详细计算也是如此。这些数据进行比较，报告的数据为FeSb 2，它在相同的白铁矿结构结晶，和FeSi，另一个不寻常的窄隙半导体。
英文摘要：
Resistivity, Hall effect, Seebeck coefficient, thermal conductivity, heat capacity, and magnetic susceptibility data are reported for CrSb2 single crystals. In spite of some unusual features in electrical transport and Hall measurements below 100 K, only one phase transition is found in the temperature range from 2 to 750 K corresponding to long-range antiferromagnetic order below T_N ~ 273 K. Many of the low temperature properties can be explained by the thermal depopulation of carriers from the conduction band into a low mobility band located approximately 16 meV below the conduction band edge, as deduced from the Hall effect data. In analogy with what occurs in Ge, the low mobility band is likely an impurity band. The Seebeck coefficient, S, is large and negative for temperatures from 2 to 300 K ranging from ~ -70\muV/K at 300 K to -4500\muV/K at 18 K. A large maximum in |S| at 18 K is likely due to phonon drag with the abrupt drop in |S| below 18 K due to the thermal depopulation of the high mobility conduction band. The large thermal conductivity between 10 and 20 K (~350 W/m/K) is consistent with this interpretation, as are detailed calculations of the Seebeck coefficient made using the complete calculated electronic structure. These data are compared to data reported for FeSb2, which crystallizes in the same marcasite structure, and FeSi, another unusual narrow-gap semiconductor.
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