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Metallic and Insulating behaviour in p-SiGe at nu = 3/2

P. T. Coleridge·R. L. Williams·J. Lapointe·P. Zawadzki
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Abstract

Shubnikov-de Haas data is presented for a p-SiGe sample exhibiting strongly insulating behaviour at nu = 3/2. In addition to the fixed points defining a high field metal- insulator transition into this phase separate fixed points can also be identified for the nu = 3 --> 2 and 2 --> 1 Integer quantum Hall transitions. Another feature of the data, that the Hall resistivity approaches zero in the insulating phase, indicates it is not a re-entrant Hall insulator. The behaviour is explained in terms of the strong exchange interactions. At integer filling factors these cause the 0 uparrow and 1 downarrow Landau levels to cross and be well separated but at non-integer values of nu screening reduces exchange effects and causes the levels to stick together. It is suggested the insulating behaviour, and high field metal/insulator transition, is a consequence of the strong exchange interactions.

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P. T. Coleridge, R. L. Williams, J. Lapointe, P. Zawadzki. 2002-08-16. Metallic and Insulating behaviour in p-SiGe at nu = 3/2. https://arxiv.org/abs/cond-mat/0208330

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