Visualizing critical correlations near the metal-insulator transition in Ga(1-x)Mn(x)As.
Electronic states in disordered conductors on the verge of localization are predicted to exhibit critical spatial characteristics indicative of the proximity to a metal-insulator phase transition. We used scanning tunneling microscopy to visualize electronic states in Ga(1-x)Mn(x)As samples close to this transition. Our measurements show that doping-induced disorder produces strong spatial variations in the local tunneling conductance across a wide range of energies. Near the Fermi energy, where spectroscopic signatures of electron-electron interaction are the most prominent, the electronic states exhibit a diverging spatial correlation length. Power-law decay of the spatial correlations is accompanied by log-normal distributions of the local density of states and multifractal spatial characteristics.
Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA.
Anthony
A
Richardella
Pedram
P
Roushan
Shawn
S
Mack
Brian
B
Zhou
David A
DA
Huse
David D
DD
Awschalom
Ali
A
Yazdani