Long-Range Order in Electronic Transport Through Disordered Metal Films

• Published in: Science (American Association for the Advancement of Science) 2008-02, Vol.319 (5867), p.1226-1229
• Main Authors: Aigner, S, Pietra, L. Della, Japha, Y, Entin-Wohlman, O, David, T, Salem, R, Folman, R, Schmiedmayer, J
• Format: Article
• Language: English
• Subjects: Atoms; Atoms & subatomic particles; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity; Electric current; Electric currents; Electrical properties of specific thin films; Electrical resistivity; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electrons; Exact sciences and technology; Geometric planes; Grain size; Magnetic fields; Magnetism; Metal films; Metals; Metals and metallic alloys; Micrometers; Microscopes; Physics
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1152458

Ultracold atom magnetic field microscopy enables the probing of current flow patterns in planar structures with unprecedented sensitivity. In polycrystalline metal (gold) films, we observed long-range correlations forming organized patterns oriented at ±45° relative to the mean current flow, even at room temperature and at length scales larger than the diffusion length or the grain size by several orders of magnitude. The preference to form patterns at these angles is a direct consequence of universal scattering properties at defects. The observed amplitude of the current direction fluctuations scales inversely to that expected from the relative thickness variations, the grain size, and the defect concentration, all determined independently by standard methods. Ultracold atom magnetometry thus enables new insight into the interplay between disorder and transport.