Visualizing Critical Correlations Near the Metal-Insulator Transition in Ga 1- x Mn x As

Abstract

Metal-Insulator Transition At near-zero temperatures, some materials undergo a metal-insulator transition and their electronic properties change from conducting to insulating. In the dilute magnetic semiconductor Ga 1− x Mn x As, a promising spintronics material, the metal-insulator transition is driven by the substitution of Ga atoms with Mn. While disorder clearly plays a key role in this transition, the influence of electron-electron correlations has been far from clear. Richardella et al. (p. 665 ; see the Perspective by Fiete and de Lozanne ) used scanning tunneling microscopy to study the electronic states of this system. The autocorrelation function of the local density of states exhibited a power law (rather than an exponential) decay at Fermi energy. Thus, electron-electron interactions are indeed crucial for understanding dilute magnetic semiconductors.