Localized versus itinerant electrons at the metal-insulator transition in Si:P

作者：Mitja Lakner, H. v. Löhneysen · 发表于：Physical Review Letters · 年份：1989 · DOI：10.1103/physrevlett.63.648 · 被引用次数：74 · 研究领域：Quantum and electron transport phenomena、Semiconductor materials and devices、Theoretical and Computational Physics

The specific heat C of uncompensated phosphorus-doped silicon with P concentration N between 0.34 and 7.3\ifmmode\times\else\texttimes\fi{}${10}^{18}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$, i.e., in the vicinity of the metal-insulator transition, has been measured over a large range of temperature (0.04 K\ensuremath{\le}T\ensuremath{\le}3 K), allowing the unambiguous detection of an anomalous contribution \ensuremath{\Delta}C\ensuremath{\sim}${T}^{\ensuremath{\alpha}}$, with \ensuremath{\alpha} becoming negative for small N. This is attributed to exchange-coupled clusters. The magnetic-field dependence of C (up to 5.7 T) allows us to deduce the relative contributions of localized and delocalized electrons and gives evidence for interactions and correlations between these.