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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 have used scanning tunneling microscopy
to visualize electronic states in Ga1‑xMnxAs 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. Our method can be used to explore critical correlations in other
materials close to a quantum critical point.
Published in Science: Report
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Joseph Henry Laboratories of Physics
Department of Physics
Jadwin Hall
Princeton University
Princeton, NJ 08544
Tel: 609.258.4390
FAX: 609.258.1006
Lab phone/fax: 609.258.9517
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