We investigate the scaling properties of eigenstates of a one-dimensional (1D) Anderson model in the presence of a constant electric field. The states show a transition from exponential to factorial localization. For infinite systems this transition can be described by a simple scaling law based on a single parameter $\lambda_{ \infty} = l_{ \infty}/l_{ \rm el}$, the ratio between the Anderson localization length $l_{ \infty}$ and the Stark localization length~$l_{ \rm el}$. For finite samples, however, the system size $N$ enters the problem as a third parameter. In that case the global structure of eigenstates is uniquely determined by two scaling parameters $\lambda_N=l_\infty/N$ and $\lambda_\infty=l_\infty/l_{ \rm el}$.
Categories: cond-mat.dis-nn