Physics

Tilting the field to expose a fraction

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Science  08 May 2015:
Vol. 348, Issue 6235, pp. 645-646
DOI: 10.1126/science.348.6235.645-d

In extremely clean, flat, and cold conductors, turning on an external magnetic field can produce the so-called quantum Hall effect (QHE), with the voltage across the sample exhibiting plateaus. The plateaus reflect the discrete energy levels of electrons in a magnetic field and can sometimes appear when only part of the level is filled: the fractional QHE. The most exotic of these states have filling factors with even denominators and may be useful in topological quantum computing. Falson et al. observed even-denominator states with filling factors 3/2 and 7/2 at the interface of MgZnO and ZnO. Interestingly, one of the states was only observable when the researchers tilted the magnetic field from the normal to the sample.

Nat. Phys. 11, 347 (2015).

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