Dresden 2003 – scientific programme
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HL: Halbleiterphysik
HL 14: Poster I
HL 14.79: Poster
Monday, March 24, 2003, 17:00–19:30, HSZ/P2
Detailed Studies of the Magnetoresistance at the Metal-Insulator Transition of Graphite — •H. Kempa and P. Esquinazi — Abt. Supraleitung und Magnetismus, Universität Leipzig, D-04103 Leipzig
The change of the longitudinal resistance Rxx of quasi 2D samples of graphite with magnetic field B applied perpendicular to the graphene planes has been studied with high resolution in the field region around the metal-insulator transition. The results indicate that the field slope α(B) = dRxx/dB depends on field and shows a maximum at the critical field Bc ∼ 0.1 T of the transition. This behavior is similar to that measured in other 2D electron-gas systems. Moreover, we show that at the transition α(B) strongly fluctuates, resembling the behavior observed in other systems like manganites, where the MIT is accompanied by a large enhancement of the 1/f noise. Our data support the existence of two phases in graphite. We compare our data with two-species percolation model of the MIT.