Anomalous Longitudinal Magnetic Field near the Surface of Copper   Conductors
  We have used ultracold atoms to characterize the magnetic field near the surface of copper conductors at room temperature carrying currents between 0.045 A and 2 A. In addition to the usual circular field we find an additional, 1000 - 10000 times smaller longitudinal field. The field changes its strength periodically with a period of 200-300 um. 
S. Kraft, A. Guenther, H. Ott, D. Wharam, C. Zimmermann, and J.   Fortagh