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中国物理学会期刊

关于多层超薄共格结构的导电性质

CSTR: 32037.14.aps.33.352

ON THE ELECTRICAL CONDUCTION OF LUCS

CSTR: 32037.14.aps.33.352
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  • 实验表明Nb/Ti多层超薄共格结构有特殊导电行为。我们认为这种行为反映了这类人工材料的超晶格能带结构特性。随着超晶格周期变小,它由金属的性质向半导体或半金属的性质过渡。超晶格调制使多层超薄共格结构中的电子态分为扩展的和在调制方向定域性很强的两种;它们在沿调制方向具有相差很大的有效质量。我们分别考虑两类电子态的贡献,计算了电阻率和电阻温度系数随超晶格周期的变化,结果显示出实验观察的行为。

     

    Layered Ultrathin Coherent Structures (LUCS) made up of transition metals Nb and Ti exhibit peculiar electrical conduction properties, which reflect the energy band charateri-stics of these artificial superlattices such that there is a transition from metallic to semiconducting or semi-metallic properties with decreasing superlattice period. Owing to the supe-rlattice modulation, there are two catagories of electronic states in LUCS: extended states and strongly localized states in the direction of modulation. Electrons in these two kinds of states have very different effective masses along the modulation direction. We have considered separately the contributions of the two kinds of electronic states, and have obtained the resistivity and its temperature coefficient which show variations with the inverse superlattice period in accordance with measurements.

     

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