Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 9: Poster 1

HL 9.71: Poster

Montag, 23. März 2009, 14:30–17:00, P2

Influence of magnetic dopants on the metal-insulator transition in semiconductors — •Jörg Teubert¹, Peter J. Klar¹, and Wolfram Heimbrodt² — ¹I.Physikalisches Institut JLU-Giessen — ²Philipps-Universität Marburg

By incorporating magnetic impurities into semiconductors, one immediately enters interesting intermediate areas between the fields of magnetism and semiconductor physics. In III-Mn-V compounds the magnetic impurity Mn serves both as the source of a large localized magnetic moment and as the source of a loosely bound hole due to its acceptor character. We will compare the transport behavior of InSb:Mn (magnetic) with InSb:Ge (non-magnetic). Both Mn and Ge form shallow acceptor levels in InSb with identical acceptor activation energies. Thus, the MIT occurs at the same critical impurity concentration and the two systems are directly comparable. However, InSb:Mn and InSb:Ge samples reveal distinct differences in their electric resistivity near the MIT. InSb:Ge shows the commonly observed behavior whereas InSb:Mn exhibits a strong enhancement of the resistivity below 10 K and pronounced negative magnetoresistance effects at 1.6 K. Both effects increase by applying hydrostatic pressure. A qualitative model explaining the observed effects based on spin effects will be presented.