Abstract Power law behavior for the zigzag transition in a Yukawa cluster T. E. Sheridan ∗ and Andrew L. Magyar † Department of Physics and Astronomy, Ohio Northern University, Ada, OH 45810 We provide direct experimental evidence that the one-dimensional (1D) to two-dimensional (2D) zigzag transition in a Yukawa cluster exhibits power law behavior. Configurations of a six-particle dusty (complex) plasma confined in a biharmonic potential well are characterized as the well anisotropy is reduced. When the anisotropy is large the particles are in a 1D straight line config- uration. As the anisotropy is decreased the cluster undergoes a zigzag transition to a 2D configu- ration. The measured dependence of cluster width on anisotropy is well described by a power law. A second transition from the zigzag to an elliptical configuration is also observed. The results are in very good agreement with a model for particles interacting through a Yukawa potential. arXiv:1001.0753v1 [physics.plasm-ph] 5 Jan 2010 $^{∗}$Electronic address: t-sheridan@onu.edu $^{†}$Present address: Department of Physics, Penn State University, University Park, PA 16802 1