Magnetopolarizability at the Metal-Insulator Transition

Michael Specht (1) , Laurent P. Lévy (1) , F. Ladieu (2) , M. Sanquer (2)

1 GHMFL - Grenoble High Magnetic Field Laboratory
2 SPEC - UMR3680 - Service de physique de l'état condensé

We have studied the ac response of a series of disordered YxSi1−x insulating samples in the vicinity of the metal-insulator transition. Far from the transition, the ac response is universal in frequency units scaled by a characteristic frequency, ωc≈g(ξc)C(ξc) governed by the critical conductance g(ξc) at the percolation threshold. A temperature-dependent characteristic field Bc∝T0.5, consistent with interference effects, is identified. As the transition is approached, intermediate frequency scales are stretched according to Δln(ωc)∝(T0T)14. We relate this stretching to the distribution of localization lengths at the transition.

Domaines: Physique [physics]

Michael Specht, Laurent P. Lévy, F. Ladieu, M. Sanquer. Magnetopolarizability at the Metal-Insulator Transition. Physical Review Letters, 1995, 75 (21), pp.3902 - 3905. ⟨10.1103/PhysRevLett.75.3902⟩. ⟨cea-01396483⟩