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Science  18 Dec 2015:
Vol. 350, Issue 6267, pp. 1482
DOI: 10.1126/science.350.6267.1482-a

In the Report “Observation of chiral currents at the magnetic domain boundary of a topological insulator” (1), we reported the observation of a chiral current in a topological insulator/ferromagnetic insulator heterostructure. The measurement used a superconducting quantum interference device (SQUID) to detect an ac magnetic field that we believed was produced by a current flowing in the sample. Depending on the conductivity of various layers of the sample, a similar signal can arise when electric coupling causes a vertical oscillation of the SQUID in the spatially varying magnetic field produced by the magnetism of the sample. We and collaborators have subsequently shown that the magnitude, shape, frequency dependence, and backgate-voltage dependence of the signal can be explained by the electric coupling artifact (2). Although this does not rule out the presence of chiral edge states in these samples, we cannot state that we have observed them. Thus, we must retract our results. This artifact does not affect other papers that used similar methods to image current in nonmagnetic samples.


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