The first precise measurement of the Casimir force between dissimilar metals is reported. The attractive force, between a Cu layer evaporated on a microelectromechanical torsional oscillator, and an Au layer deposited on an Al2O3 sphere, was measured dynamically with a noise level of 6 fN/Hz. Measurements were performed for separations in the 0.2-2 μm range. The results agree to better than 1% in the 0.2-0.5 μm range with a theoretical model that takes into account the finite conductivity and roughness of the two metals. The observed discrepancies, which are much larger than the experimental precision, can be attributed to a lack of a complete characterization of the optical properties of the specific samples used in the experiment.
@article{arxiv.quant-ph/0306136,
title = {Measurement of the Casimir force between dissimilar metals},
author = {R. S. Decca and D. López and E. Fischbach and D. E. Krause},
journal= {arXiv preprint arXiv:quant-ph/0306136},
year = {2009}
}