Magnetoresistance over the intermediate localization regime in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum wires

A low-temperature (0.04<T<2 K), low-magnetic-field (B<300 mT) transport study of GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As wires shows giant negative magnetoresistance, induced by reducing T, confirming one-dimensional localization. The magnetoresistance is described by R(T,B)=${\mathit{R}}_0$+${\mathit{R}}_1$(T) +${\mathit{R}}_2$(T)/[1+(B/ΔB${)}^2$], and the T-dependent terms exhibit power laws, ${\mathit{R}}_1$(T)∼${\mathit{T}}^{\mathrm{-}1/2}$ and ${\mathit{R}}_2$(T)∼${\mathit{T}}^{\mathrm{-}1}$, characteristic of electron interaction and quantum interference effects, respectively. At the lowest T, ${\mathit{R}}_1$(T) and ${\mathit{R}}_2$(T) saturate to a T-independent value indicating that the effective wire length may not be increased further by reducing T, below ${\mathit{T}}_{\mathit{c}}$. The results demonstrate a temperature-induced dimensional crossover, from D=1 to 0, in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum wires.