A current image is taken at 50meV in the twin domain boundary of underdoped Ca(Fe1-xCox)2As2. The static unidirectional electronic structures change directionality by 90 degrees across the twin boundary. The autocorrelations of the respective domains are shown in the insets; center of self-similarity peaks (gray lines) are separated by ~8aFe-Fe. T.-M. Chuang, M. P. Allan, Jinho Lee, Yang Xie, Ni Ni, S. L. Bud'ko, G. S. Boebinger, P. C. Canfield, J. C. Davis. Science 327, 181 (2010).

Image courtesy: Dr. J.C. Seamus Davis, Cornell University.