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Electronic transport measurements guide the discovery and characterization of quantum materials. The Biot-Savart law dictates that the motion of electrons generates a stray magnetic field during such a transport experiment. I will show how imaging these magnetic fields with a scanning SQUID microscope allows us the determine the path that current takes through our devices. I will then discuss the application of this approach to the quantum anomalous Hall regime in magnetically doped topological insulators. Using local information about the current distribution, I will show how bulk conduction processes give rise to a quantized Hall effect. I will then describe our efforts to visualize the breakdown of the quantum anomalous Hall effect under the application of large bias currents.

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Dr. George Matthew Ferguson (SFB1238/Kolloquium), MPI Dresden
Seminar Room of the Institute of Physics II
Contact: Torsten Roeper/ Erwann Bocquillon