title: Asymmetric metal-insulator transition in disordered ferromagnetic films.
abstract: We present experimental data and a theoretical interpretation of the conductance near the metal-insulator transition in thin ferromagnetic Gd films of thickness b ≈ 2-10  nm. A large phase relaxation rate caused by scattering of quasiparticles off spin-wave excitations renders the dephasing length L(ϕ) ≲ b in the range of sheet resistances considered, so that the effective dimension is d = 3. The conductivity data at different stages of disorder obey a fractional power-law temperature dependence and collapse onto two scaling curves for the metallic and insulating regimes, indicating an asymmetric metal-insulator transition with two distinctly different critical exponents; the best fit is obtained for a dynamical exponent z ≈ 2.5 and a correlation (localization) length critical exponent ν- ≈ 1.4 (ν+ ≈ 0.8) on the metallic (insulating) side.
authors.affiliation: Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA.
authors.forename: R
authors.initials: R
authors.lastname: Misra
authors.forename: A F
authors.initials: AF
authors.lastname: Hebard
authors.forename: K A
authors.initials: KA
authors.lastname: Muttalib
authors.forename: P
authors.initials: P
authors.lastname: Wölfle